=item Functions for SCALARs or strings
X<scalar> X<string> X<character>
+=for Pod::Functions =String
+
C<chomp>, C<chop>, C<chr>, C<crypt>, C<fc>, C<hex>, C<index>, C<lc>,
C<lcfirst>, C<length>, C<oct>, C<ord>, C<pack>, C<q//>, C<qq//>, C<reverse>,
C<rindex>, C<sprintf>, C<substr>, C<tr///>, C<uc>, C<ucfirst>, C<y///>
+C<fc> is available only if the C<"fc"> feature is enabled or if it is
+prefixed with C<CORE::>. The C<"fc"> feature is enabled automatically
+with a C<use v5.16> (or higher) declaration in the current scope.
+
+
=item Regular expressions and pattern matching
X<regular expression> X<regex> X<regexp>
-C<m//>, C<pos>, C<quotemeta>, C<s///>, C<split>, C<study>, C<qr//>
+=for Pod::Functions =Regexp
+
+C<m//>, C<pos>, C<qr//>, C<quotemeta>, C<s///>, C<split>, C<study>
=item Numeric functions
X<numeric> X<number> X<trigonometric> X<trigonometry>
+=for Pod::Functions =Math
+
C<abs>, C<atan2>, C<cos>, C<exp>, C<hex>, C<int>, C<log>, C<oct>, C<rand>,
C<sin>, C<sqrt>, C<srand>
=item Functions for real @ARRAYs
X<array>
+=for Pod::Functions =ARRAY
+
C<each>, C<keys>, C<pop>, C<push>, C<shift>, C<splice>, C<unshift>, C<values>
=item Functions for list data
X<list>
+=for Pod::Functions =LIST
+
C<grep>, C<join>, C<map>, C<qw//>, C<reverse>, C<sort>, C<unpack>
=item Functions for real %HASHes
X<hash>
+=for Pod::Functions =HASH
+
C<delete>, C<each>, C<exists>, C<keys>, C<values>
=item Input and output functions
X<I/O> X<input> X<output> X<dbm>
+=for Pod::Functions =I/O
+
C<binmode>, C<close>, C<closedir>, C<dbmclose>, C<dbmopen>, C<die>, C<eof>,
C<fileno>, C<flock>, C<format>, C<getc>, C<print>, C<printf>, C<read>,
-C<readdir>, C<rewinddir>, C<say>, C<seek>, C<seekdir>, C<select>, C<syscall>,
-C<sysread>, C<sysseek>, C<syswrite>, C<tell>, C<telldir>, C<truncate>,
-C<warn>, C<write>
+C<readdir>, C<readline> C<rewinddir>, C<say>, C<seek>, C<seekdir>, C<select>,
+C<syscall>, C<sysread>, C<sysseek>, C<syswrite>, C<tell>, C<telldir>,
+C<truncate>, C<warn>, C<write>
+
+C<say> is available only if the C<"say"> feature is enabled or if it is
+prefixed with C<CORE::>. The C<"say"> feature is enabled automatically
+with a C<use v5.10> (or higher) declaration in the current scope.
=item Functions for fixed-length data or records
-C<pack>, C<read>, C<syscall>, C<sysread>, C<syswrite>, C<unpack>, C<vec>
+=for Pod::Functions =Binary
+
+C<pack>, C<read>, C<syscall>, C<sysread>, C<sysseek>, C<syswrite>, C<unpack>,
+C<vec>
=item Functions for filehandles, files, or directories
X<file> X<filehandle> X<directory> X<pipe> X<link> X<symlink>
+=for Pod::Functions =File
+
C<-I<X>>, C<chdir>, C<chmod>, C<chown>, C<chroot>, C<fcntl>, C<glob>,
C<ioctl>, C<link>, C<lstat>, C<mkdir>, C<open>, C<opendir>,
C<readlink>, C<rename>, C<rmdir>, C<stat>, C<symlink>, C<sysopen>,
=item Keywords related to the control flow of your Perl program
X<control flow>
-C<caller>, C<continue>, C<die>, C<do>,
+=for Pod::Functions =Flow
+
+C<break>, C<caller>, C<continue>, C<die>, C<do>,
C<dump>, C<eval>, C<evalbytes> C<exit>,
C<__FILE__>, C<goto>, C<last>, C<__LINE__>, C<next>, C<__PACKAGE__>,
C<redo>, C<return>, C<sub>, C<__SUB__>, C<wantarray>
-C<__SUB__> is only available with a C<use v5.16> (or higher) declaration or
-with the C<"current_sub"> feature (see L<feature>).
-
-=item Keywords related to the switch feature
-
-C<break>, C<continue>, C<default>, C<given>, C<when>
+C<break> is available only if you enable the experimental C<"switch">
+feature or use the C<CORE::> prefix. The C<"switch"> feature also enables
+the C<default>, C<given> and C<when> statements, which are documented in
+L<perlsyn/"Switch Statements">. The C<"switch"> feature is enabled
+automatically with a C<use v5.10> (or higher) declaration in the current
+scope. In Perl v5.14 and earlier, C<continue> required the C<"switch">
+feature, like the other keywords.
-Except for C<continue>, these are available only if you enable the
-C<"switch"> feature or use the C<CORE::> prefix.
-See L<feature> and L<perlsyn/"Switch Statements">.
-Alternately, include a C<use v5.10> or later to the current scope. In Perl
-5.14 and earlier, C<continue> required the C<"switch"> feature, like the
-other keywords.
+C<evalbytes> is only available with the C<"evalbytes"> feature (see
+L<feature>) or if prefixed with C<CORE::>. C<__SUB__> is only available
+with the C<"current_sub"> feature or if prefixed with C<CORE::>. Both
+the C<"evalbytes"> and C<"current_sub"> features are enabled automatically
+with a C<use v5.16> (or higher) declaration in the current scope.
=item Keywords related to scoping
+=for Pod::Functions =Namespace
+
C<caller>, C<import>, C<local>, C<my>, C<our>, C<package>, C<state>, C<use>
-C<state> is available only if the C<"state"> feature
-is enabled or if it is prefixed with C<CORE::>. See
-L<feature>. Alternately, include a C<use v5.10> or later to the current scope.
+C<state> is available only if the C<"state"> feature is enabled or if it is
+prefixed with C<CORE::>. The C<"state"> feature is enabled automatically
+with a C<use v5.10> (or higher) declaration in the current scope.
=item Miscellaneous functions
-C<defined>, C<dump>, C<eval>, C<evalbytes>,
-C<formline>, C<local>, C<my>, C<our>,
-C<reset>, C<scalar>, C<state>, C<undef>, C<wantarray>
+=for Pod::Functions =Misc
+
+C<defined>, C<formline>, C<lock>, C<prototype>, C<reset>, C<scalar>, C<undef>
=item Functions for processes and process groups
X<process> X<pid> X<process id>
+=for Pod::Functions =Process
+
C<alarm>, C<exec>, C<fork>, C<getpgrp>, C<getppid>, C<getpriority>, C<kill>,
C<pipe>, C<qx//>, C<readpipe>, C<setpgrp>,
C<setpriority>, C<sleep>, C<system>,
=item Keywords related to Perl modules
X<module>
+=for Pod::Functions =Modules
+
C<do>, C<import>, C<no>, C<package>, C<require>, C<use>
=item Keywords related to classes and object-orientation
X<object> X<class> X<package>
+=for Pod::Functions =Objects
+
C<bless>, C<dbmclose>, C<dbmopen>, C<package>, C<ref>, C<tie>, C<tied>,
C<untie>, C<use>
=item Low-level socket functions
X<socket> X<sock>
+=for Pod::Functions =Socket
+
C<accept>, C<bind>, C<connect>, C<getpeername>, C<getsockname>,
C<getsockopt>, C<listen>, C<recv>, C<send>, C<setsockopt>, C<shutdown>,
C<socket>, C<socketpair>
=item System V interprocess communication functions
X<IPC> X<System V> X<semaphore> X<shared memory> X<memory> X<message>
+=for Pod::Functions =SysV
+
C<msgctl>, C<msgget>, C<msgrcv>, C<msgsnd>, C<semctl>, C<semget>, C<semop>,
C<shmctl>, C<shmget>, C<shmread>, C<shmwrite>
=item Fetching user and group info
X<user> X<group> X<password> X<uid> X<gid> X<passwd> X</etc/passwd>
+=for Pod::Functions =User
+
C<endgrent>, C<endhostent>, C<endnetent>, C<endpwent>, C<getgrent>,
C<getgrgid>, C<getgrnam>, C<getlogin>, C<getpwent>, C<getpwnam>,
C<getpwuid>, C<setgrent>, C<setpwent>
=item Fetching network info
X<network> X<protocol> X<host> X<hostname> X<IP> X<address> X<service>
+=for Pod::Functions =Network
+
C<endprotoent>, C<endservent>, C<gethostbyaddr>, C<gethostbyname>,
C<gethostent>, C<getnetbyaddr>, C<getnetbyname>, C<getnetent>,
C<getprotobyname>, C<getprotobynumber>, C<getprotoent>,
=item Time-related functions
X<time> X<date>
+=for Pod::Functions =Time
+
C<gmtime>, C<localtime>, C<time>, C<times>
=item Non-function keywords
-C<AUTOLOAD>, C<BEGIN>, C<CHECK>, C<CORE>, C<DESTROY>, C<END>, C<INIT>,
-C<UNITCHECK>, C<__DATA__>, C<__END__>, C<and>, C<cmp>, C<else>, C<elseif>,
-C<elsif>, C<eq>, C<for>, C<foreach>, C<ge>, C<gt>, C<if>, C<le>, C<lt>, C<ne>,
-C<not>, C<or>, C<unless>, C<until>, C<while>, C<x>, C<xor>
+=for Pod::Functions =!Non-functions
+
+C<and>, C<AUTOLOAD>, C<BEGIN>, C<CHECK>, C<cmp>, C<CORE>, C<__DATA__>,
+C<default>, C<DESTROY>, C<else>, C<elseif>, C<elsif>, C<END>, C<__END__>,
+C<eq>, C<for>, C<foreach>, C<ge>, C<given>, C<gt>, C<if>, C<INIT>, C<le>,
+C<lt>, C<ne>, C<not>, C<or>, C<UNITCHECK>, C<unless>, C<until>, C<when>,
+C<while>, C<x>, C<xor>
=back
=item -X
+=for Pod::Functions a file test (-r, -x, etc)
+
A file test, where X is one of the letters listed below. This unary
operator takes one argument, either a filename, a filehandle, or a dirhandle,
and tests the associated file to see if something is true about it. If the
-M Script start time minus file modification time, in days.
-A Same for access time.
- -C Same for inode change time (Unix, may differ for other platforms)
+ -C Same for inode change time (Unix, may differ for other
+ platforms)
Example:
print "Text\n" if -T _;
print "Binary\n" if -B _;
-As of Perl 5.9.1, as a form of purely syntactic sugar, you can stack file
+As of Perl 5.10.0, as a form of purely syntactic sugar, you can stack file
test operators, in a way that C<-f -w -x $file> is equivalent to
C<-x $file && -w _ && -f _>. (This is only fancy fancy: if you use
the return value of C<-f $file> as an argument to another filetest
=item abs
+=for Pod::Functions absolute value function
+
Returns the absolute value of its argument.
If VALUE is omitted, uses C<$_>.
=item accept NEWSOCKET,GENERICSOCKET
X<accept>
+=for Pod::Functions accept an incoming socket connect
+
Accepts an incoming socket connect, just as accept(2)
does. Returns the packed address if it succeeded, false otherwise.
See the example in L<perlipc/"Sockets: Client/Server Communication">.
=item alarm
+=for Pod::Functions schedule a SIGALRM
+
Arranges to have a SIGALRM delivered to this process after the
specified number of wallclock seconds has elapsed. If SECONDS is not
specified, the value stored in C<$_> is used. (On some machines,
=item atan2 Y,X
X<atan2> X<arctangent> X<tan> X<tangent>
+=for Pod::Functions arctangent of Y/X in the range -PI to PI
+
Returns the arctangent of Y/X in the range -PI to PI.
For the tangent operation, you may use the C<Math::Trig::tan>
=item bind SOCKET,NAME
X<bind>
+=for Pod::Functions binds an address to a socket
+
Binds a network address to a socket, just as bind(2)
does. Returns true if it succeeded, false otherwise. NAME should be a
packed address of the appropriate type for the socket. See the examples in
=item binmode FILEHANDLE
+=for Pod::Functions prepare binary files for I/O
+
Arranges for FILEHANDLE to be read or written in "binary" or "text"
mode on systems where the run-time libraries distinguish between
binary and text files. If FILEHANDLE is an expression, the value is
=item bless REF
+=for Pod::Functions create an object
+
This function tells the thingy referenced by REF that it is now an object
in the CLASSNAME package. If CLASSNAME is omitted, the current package
is used. Because a C<bless> is often the last thing in a constructor,
it returns the reference for convenience. Always use the two-argument
version if a derived class might inherit the function doing the blessing.
-SeeL<perlobj> for more about the blessing (and blessings) of objects.
+See
L<perlobj> for more about the blessing (and blessings) of objects.
Consider always blessing objects in CLASSNAMEs that are mixed case.
Namespaces with all lowercase names are considered reserved for
=item break
+=for Pod::Functions +switch break out of a C<given> block
+
Break out of a C<given()> block.
-This keyword is enabled by the C<"switch"> feature: see
-L<feature> for more information. You can also access it by
-prefixing it with C<CORE::>. Alternately, include a C<use
-v5.10> or later to the current scope.
+This keyword is enabled by the C<"switch"> feature; see L<feature> for
+more information on C<"switch">. You can also access it by prefixing it
+with C<CORE::>. Alternatively, include a C<use v5.10> or later to the
+current scope.
=item caller EXPR
X<caller> X<call stack> X<stack> X<stack trace>
=item caller
+=for Pod::Functions get context of the current subroutine call
+
Returns the context of the current subroutine call. In scalar context,
returns the caller's package name if there I<is> a caller (that is, if
we're in a subroutine or C<eval> or C<require>) and the undefined value
subroutine happens to have been deleted from the symbol table.
C<$hasargs> is true if a new instance of C<@_> was set up for the frame.
C<$hints> and C<$bitmask> contain pragmatic hints that the caller was
-compiled with. The C<$hints> and C<$bitmask> values are subject to change
-between versions of Perl, and are not meant for external use.
+compiled with. C<$hints> corresponds to C<$^H>, and C<$bitmask>
+corresponds to C<${^WARNING_BITS}>. The
+C<$hints> and C<$bitmask> values are subject
+to change between versions of Perl, and are not meant for external use.
C<$hinthash> is a reference to a hash containing the value of C<%^H> when the
caller was compiled, or C<undef> if C<%^H> was empty. Do not modify the values
=item chdir
+=for Pod::Functions change your current working directory
+
Changes the working directory to EXPR, if possible. If EXPR is omitted,
changes to the directory specified by C<$ENV{HOME}>, if set; if not,
changes to the directory specified by C<$ENV{LOGDIR}>. (Under VMS, the
=item chmod LIST
X<chmod> X<permission> X<mode>
+=for Pod::Functions changes the permissions on a list of files
+
Changes the permissions of a list of files. The first element of the
list must be the numeric mode, which should probably be an octal
number, and which definitely should I<not> be a string of octal digits:
=item chomp
+=for Pod::Functions remove a trailing record separator from a string
+
This safer version of L</chop> removes any trailing string
that corresponds to the current value of C<$/> (also known as
$INPUT_RECORD_SEPARATOR in the C<English> module). It returns the total
=item chop
+=for Pod::Functions remove the last character from a string
+
Chops off the last character of a string and returns the character
chopped. It is much more efficient than C<s/.$//s> because it neither
scans nor copies the string. If VARIABLE is omitted, chops C<$_>.
=item chown LIST
X<chown> X<owner> X<user> X<group>
+=for Pod::Functions change the ownership on a list of files
+
Changes the owner (and group) of a list of files. The first two
elements of the list must be the I<numeric> uid and gid, in that
order. A value of -1 in either position is interpreted by most
=item chr
+=for Pod::Functions get character this number represents
+
Returns the character represented by that NUMBER in the character set.
For example, C<chr(65)> is C<"A"> in either ASCII or Unicode, and
chr(0x263a) is a Unicode smiley face.
=item chroot
+=for Pod::Functions make directory new root for path lookups
+
This function works like the system call by the same name: it makes the
named directory the new root directory for all further pathnames that
begin with a C</> by your process and all its children. (It doesn't
=item close
+=for Pod::Functions close file (or pipe or socket) handle
+
Closes the file or pipe associated with the filehandle, flushes the IO
buffers, and closes the system file descriptor. Returns true if those
operations succeed and if no error was reported by any PerlIO
=item closedir DIRHANDLE
X<closedir>
+=for Pod::Functions close directory handle
+
Closes a directory opened by C<opendir> and returns the success of that
system call.
=item connect SOCKET,NAME
X<connect>
+=for Pod::Functions connect to a remote socket
+
Attempts to connect to a remote socket, just like connect(2).
Returns true if it succeeded, false otherwise. NAME should be a
packed address of the appropriate type for the socket. See the examples in
=item continue
+=for Pod::Functions optional trailing block in a while or foreach
+
When followed by a BLOCK, C<continue> is actually a
flow control statement rather than a function. If
there is a C<continue> BLOCK attached to a BLOCK (typically in a C<while> or
=item cos
+=for Pod::Functions cosine function
+
Returns the cosine of EXPR (expressed in radians). If EXPR is omitted,
takes the cosine of C<$_>.
X<crypt> X<digest> X<hash> X<salt> X<plaintext> X<password>
X<decrypt> X<cryptography> X<passwd> X<encrypt>
+=for Pod::Functions one-way passwd-style encryption
+
Creates a digest string exactly like the crypt(3) function in the C
library (assuming that you actually have a version there that has not
been extirpated as a potential munition).
=item dbmclose HASH
X<dbmclose>
+=for Pod::Functions breaks binding on a tied dbm file
+
[This function has been largely superseded by the C<untie> function.]
Breaks the binding between a DBM file and a hash.
=item dbmopen HASH,DBNAME,MASK
X<dbmopen> X<dbm> X<ndbm> X<sdbm> X<gdbm>
+=for Pod::Functions create binding on a tied dbm file
+
[This function has been largely superseded by the
L<tie|/tie VARIABLE,CLASSNAME,LIST> function.]
Portability issues: L<perlport/dbmopen>.
-=item default BLOCK
-
-Within a C<foreach> or a C<given>, a C<default> BLOCK acts like a C<when>
-that's always true. Only available after Perl 5.10, and only if the
-C<switch> feature has been requested or if the keyword is prefixed with
-C<CORE::>. See L</when>.
-
=item defined EXPR
X<defined> X<undef> X<undefined>
=item defined
+=for Pod::Functions test whether a value, variable, or function is defined
+
Returns a Boolean value telling whether EXPR has a value other than
the undefined value C<undef>. If EXPR is not present, C<$_> is
checked.
=item delete EXPR
X<delete>
+=for Pod::Functions deletes a value from a hash
+
Given an expression that specifies an element or slice of a hash, C<delete>
deletes the specified elements from that hash so that exists() on that element
no longer returns true. Setting a hash element to the undefined value does
of composite types">.
%hash = (foo => 11, bar => 22, baz => 33);
- $scalar = delete $hash{foo}; # $scalar is 11
- $scalar = delete @hash{qw(foo bar)}; # $scalar is 22
- @array = delete @hash{qw(foo bar baz)}; # @array is (undef,undef,33)
+ $scalar = delete $hash{foo}; # $scalar is 11
+ $scalar = delete @hash{qw(foo bar)}; # $scalar is 22
+ @array = delete @hash{qw(foo baz)}; # @array is (undef,33)
The following (inefficiently) deletes all the values of %HASH and @ARRAY:
=item die LIST
X<die> X<throw> X<exception> X<raise> X<$@> X<abort>
+=for Pod::Functions raise an exception or bail out
+
C<die> raises an exception. Inside an C<eval> the error message is stuffed
into C<$@> and the C<eval> is terminated with the undefined value.
If the exception is outside of all enclosing C<eval>s, then the uncaught
eval { ... ; die Some::Module::Exception->new( FOO => "bar" ) };
if (my $ev_err = $@) {
- if (blessed($ev_err) && $ev_err->isa("Some::Module::Exception")) {
+ if (blessed($ev_err)
+ && $ev_err->isa("Some::Module::Exception")) {
# handle Some::Module::Exception
}
else {
=item do BLOCK
X<do> X<block>
+=for Pod::Functions turn a BLOCK into a TERM
+
Not really a function. Returns the value of the last command in the
sequence of commands indicated by BLOCK. When modified by the C<while> or
C<until> loop modifier, executes the BLOCK once before testing the loop
=item do SUBROUTINE(LIST)
X<do>
-This form of subroutine call is deprecated. SUBROUTINE can be a bareword,
-a scalar variable or a subroutine beginning with C<&>.
+This form of subroutine call is deprecated. SUBROUTINE can be a bareword
+or scalar variable.
=item do EXPR
X<do>
do 'stat.pl';
-is just like
+is largely like
eval `cat stat.pl`;
-except that it's more efficient and concise, keeps track of the current
+except that it's more concise, runs no external processes, keeps track of
+the current
filename for error messages, searches the C<@INC> directories, and updates
C<%INC> if the file is found. See L<perlvar/@INC> and L<perlvar/%INC> for
these variables. It also differs in that code evaluated with C<do FILENAME>
=item dump LABEL
X<dump> X<core> X<undump>
+=item dump EXPR
+
=item dump
+=for Pod::Functions create an immediate core dump
+
This function causes an immediate core dump. See also the B<-u>
command-line switch in L<perlrun>, which does the same thing.
Primarily this is so that you can use the B<undump> program (not
program. When the new binary is executed it will begin by executing
a C<goto LABEL> (with all the restrictions that C<goto> suffers).
Think of it as a goto with an intervening core dump and reincarnation.
-If C<LABEL> is omitted, restarts the program from the top.
+If C<LABEL> is omitted, restarts the program from the top. The
+C<dump EXPR> form, available starting in Perl 5.18.0, allows a name to be
+computed at run time, being otherwise identical to C<dump LABEL>.
B<WARNING>: Any files opened at the time of the dump will I<not>
be open any more when the program is reincarnated, with possible
it as C<CORE::dump()>, if you don't want to be warned against a possible
typo.
+Unlike most named operators, this has the same precedence as assignment.
+It is also exempt from the looks-like-a-function rule, so
+C<dump ("foo")."bar"> will cause "bar" to be part of the argument to
+C<dump>.
+
Portability issues: L<perlport/dump>.
=item each HASH
=item each EXPR
+=for Pod::Functions retrieve the next key/value pair from a hash
+
When called on a hash in list context, returns a 2-element list
consisting of the key and value for the next element of a hash. In Perl
5.12 and later only, it will also return the index and value for the next
while (($key,$value) = each $hashref) { ... }
+As of Perl 5.18 you can use a bare C<each> in a C<while> loop,
+which will set C<$_> on every iteration.
+
+ while(each %ENV) {
+ print "$_=$ENV{$_}\n";
+ }
+
To avoid confusing would-be users of your code who are running earlier
versions of Perl with mysterious syntax errors, put this sort of thing at
the top of your file to signal that your code will work I<only> on Perls of
use 5.012; # so keys/values/each work on arrays
use 5.014; # so keys/values/each work on scalars (experimental)
+ use 5.018; # so each assigns to $_ in a lone while test
See also C<keys>, C<values>, and C<sort>.
=item eof
+=for Pod::Functions test a filehandle for its end
+
Returns 1 if the next read on FILEHANDLE will return end of file I<or> if
FILEHANDLE is not open. FILEHANDLE may be an expression whose value
gives the real filehandle. (Note that this function actually
print "--------------\n";
}
print;
- last if eof(); # needed if we're reading from a terminal
+ last if eof(); # needed if we're reading from a terminal
}
Practical hint: you almost never need to use C<eof> in Perl, because the
=item eval
+=for Pod::Functions catch exceptions or compile and run code
+
In the first form, the return value of EXPR is parsed and executed as if it
were a little Perl program. The value of the expression (which is itself
determined within scalar context) is first parsed, and if there were no
{
my $e;
{
- local $@; # protect existing $@
- eval { test_repugnancy() };
- # $@ =~ /nefarious/ and die $@; # Perl 5.14 and higher only
- $@ =~ /nefarious/ and $e = $@;
+ local $@; # protect existing $@
+ eval { test_repugnancy() };
+ # $@ =~ /nefarious/ and die $@; # Perl 5.14 and higher only
+ $@ =~ /nefarious/ and $e = $@;
}
die $e if defined $e
}
C<eval BLOCK> does I<not> count as a loop, so the loop control statements
C<next>, C<last>, or C<redo> cannot be used to leave or restart the block.
-An C<eval ''> executed within the C<DB> package doesn't see the usual
+An C<eval ''> executed within a subroutine defined
+in the C<DB> package doesn't see the usual
surrounding lexical scope, but rather the scope of the first non-DB piece
of code that called it. You don't normally need to worry about this unless
you are writing a Perl debugger.
=item evalbytes
+=for Pod::Functions +evalbytes similar to string eval, but intend to parse a bytestream
+
This function is like L</eval> with a string argument, except it always
parses its argument, or C<$_> if EXPR is omitted, as a string of bytes. A
string containing characters whose ordinal value exceeds 255 results in an
=item exec PROGRAM LIST
+=for Pod::Functions abandon this program to run another
+
The C<exec> function executes a system command I<and never returns>;
use C<system> instead of C<exec> if you want it to return. It fails and
returns false only if the command does not exist I<and> it is executed
directly instead of via your system's command shell (see below).
Since it's a common mistake to use C<exec> instead of C<system>, Perl
-warns you if there is a following statement that isn't C<die>, C<warn>,
-or C<exit> (if C<-w> is set--but you always do that, right?). If you
-I<really> want to follow an C<exec> with some other statement, you
-can use one of these styles to avoid the warning:
+warns you if C<exec> is called in void context and if there is a following
+statement that isn't C<die>, C<warn>, or C<exit> (if C<-w> is set--but
+you always do that, right?). If you I<really> want to follow an C<exec>
+with some other statement, you can use one of these styles to avoid the warning:
exec ('foo') or print STDERR "couldn't exec foo: $!";
{ exec ('foo') }; print STDERR "couldn't exec foo: $!";
it tried to run a program named I<"echo surprise">, didn't find it, and set
C<$?> to a non-zero value indicating failure.
-Beginning with v5.6.0, Perl attempts to flush all files opened for
-output before the exec, but this may not be supported on some platforms
-(see L<perlport>). To be safe, you may need to set C<$|> ($AUTOFLUSH
-in English) or call the C<autoflush()> method of C<IO::Handle> on any
-open handles to avoid lost output.
+Perl attempts to flush all files opened for output before the exec,
+but this may not be supported on some platforms (see L<perlport>).
+To be safe, you may need to set C<$|> ($AUTOFLUSH in English) or
+call the C<autoflush()> method of C<IO::Handle> on any open handles
+to avoid lost output.
Note that C<exec> will not call your C<END> blocks, nor will it invoke
C<DESTROY> methods on your objects.
=item exists EXPR
X<exists> X<autovivification>
+=for Pod::Functions test whether a hash key is present
+
Given an expression that specifies an element of a hash, returns true if the
specified element in the hash has ever been initialized, even if the
corresponding value is undefined.
if (exists &{$ref->{A}{B}{$key}}) { }
-Although the mostly deeply nested array or hash will not spring into
+Although the most deeply nested array or hash element will not spring into
existence just because its existence was tested, any intervening ones will.
Thus C<< $ref->{"A"} >> and C<< $ref->{"A"}->{"B"} >> will spring
into existence due to the existence test for the $key element above.
=item exit
+=for Pod::Functions terminate this program
+
Evaluates EXPR and exits immediately with that value. Example:
$ans = <STDIN>;
themselves abort the exit. Likewise any object destructors that need to
be called are called before the real exit. C<END> routines and destructors
can change the exit status by modifying C<$?>. If this is a problem, you
-can call C<POSIX:_exit($status)> to avoid END and destructor processing.
+can call C<POSIX::_exit($status)> to avoid END and destructor processing.
See L<perlmod> for details.
Portability issues: L<perlport/exit>.
=item exp
+=for Pod::Functions raise I<e> to a power
+
Returns I<e> (the natural logarithm base) to the power of EXPR.
If EXPR is omitted, gives C<exp($_)>.
=item fc
+=for Pod::Functions +fc return casefolded version of a string
+
Returns the casefolded version of EXPR. This is the internal function
implementing the C<\F> escape in double-quoted strings.
Roughly, if you ever found yourself writing this
- lc($this) eq lc($that) # Wrong!
+ lc($this) eq lc($that) # Wrong!
# or
- uc($this) eq uc($that) # Also wrong!
+ uc($this) eq uc($that) # Also wrong!
# or
- $this =~ /\Q$that/i # Right!
+ $this =~ /^\Q$that\E\z/i # Right!
Now you can write
And get the correct results.
-Perl only implements the full form of casefolding.
+Perl only implements the full form of casefolding,
+but you can access the simple folds using L<Unicode::UCD/casefold()> and
+L<Unicode::UCD/prop_invmap()>.
For further information on casefolding, refer to
the Unicode Standard, specifically sections 3.13 C<Default Case Operations>,
4.2 C<Case-Normative>, and 5.18 C<Case Mappings>,
=item fcntl FILEHANDLE,FUNCTION,SCALAR
X<fcntl>
+=for Pod::Functions file control system call
+
Implements the fcntl(2) function. You'll probably have to say
use Fcntl;
=item __FILE__
X<__FILE__>
+=for Pod::Functions the name of the current source file
+
A special token that returns the name of the file in which it occurs.
=item fileno FILEHANDLE
X<fileno>
+=for Pod::Functions return file descriptor from filehandle
+
Returns the file descriptor for a filehandle, or undefined if the
filehandle is not open. If there is no real file descriptor at the OS
level, as can happen with filehandles connected to memory objects via
=item flock FILEHANDLE,OPERATION
X<flock> X<lock> X<locking>
+=for Pod::Functions lock an entire file with an advisory lock
+
Calls flock(2), or an emulation of it, on FILEHANDLE. Returns true
for success, false on failure. Produces a fatal error if used on a
machine that doesn't implement flock(2), fcntl(2) locking, or lockf(3).
Here's a mailbox appender for BSD systems.
- use Fcntl qw(:flock SEEK_END); # import LOCK_* and SEEK_END constants
+ # import LOCK_* and SEEK_END constants
+ use Fcntl qw(:flock SEEK_END);
sub lock {
my ($fh) = @_;
=item fork
X<fork> X<child> X<parent>
+=for Pod::Functions create a new process just like this one
+
Does a fork(2) system call to create a new process running the
same program at the same point. It returns the child pid to the
parent process, C<0> to the child process, or C<undef> if the fork is
example, using copy-on-write technology on data pages), making it the
dominant paradigm for multitasking over the last few decades.
-Beginning with v5.6.0, Perl attempts to flush all files opened for
+Perl attempts to flush all files opened for
output before forking the child process, but this may not be supported
on some platforms (see L<perlport>). To be safe, you may need to set
C<$|> ($AUTOFLUSH in English) or call the C<autoflush()> method of
=item format
X<format>
+=for Pod::Functions declare a picture format with use by the write() function
+
Declare a picture format for use by the C<write> function. For
example:
=item formline PICTURE,LIST
X<formline>
+=for Pod::Functions internal function used for formats
+
This is an internal function used by C<format>s, though you may call it,
too. It formats (see L<perlform>) a list of values according to the
contents of PICTURE, placing the output into the format output
=item getc
+=for Pod::Functions get the next character from the filehandle
+
Returns the next character from the input file attached to FILEHANDLE,
or the undefined value at end of file or if there was an error (in
the latter case C<$!> is set). If FILEHANDLE is omitted, reads from
=item getlogin
X<getlogin> X<login>
+=for Pod::Functions return who logged in at this tty
+
This implements the C library function of the same name, which on most
systems returns the current login from F</etc/utmp>, if any. If it
returns the empty string, use C<getpwuid>.
=item getpeername SOCKET
X<getpeername> X<peer>
+=for Pod::Functions find the other end of a socket connection
+
Returns the packed sockaddr address of the other end of the SOCKET
connection.
=item getpgrp PID
X<getpgrp> X<group>
+=for Pod::Functions get process group
+
Returns the current process group for the specified PID. Use
a PID of C<0> to get the current process group for the
current process. Will raise an exception if used on a machine that
=item getppid
X<getppid> X<parent> X<pid>
+=for Pod::Functions get parent process ID
+
Returns the process id of the parent process.
-Note for Linux users: on Linux, the C functions C<getpid()> and
-C<getppid()> return different values from different threads. In order to
-be portable, this behavior is not reflected by the Perl-level function
-C<getppid()>, that returns a consistent value across threads. If you want
-to call the underlying C<getppid()>, you may use the CPAN module
-C<Linux::Pid>.
+Note for Linux users: Between v5.8.1 and v5.16.0 Perl would work
+around non-POSIX thread semantics the minority of Linux systems (and
+Debian GNU/kFreeBSD systems) that used LinuxThreads, this emulation
+has since been removed. See the documentation for L<$$|perlvar/$$> for
+details.
Portability issues: L<perlport/getppid>.
=item getpriority WHICH,WHO
X<getpriority> X<priority> X<nice>
+=for Pod::Functions get current nice value
+
Returns the current priority for a process, a process group, or a user.
(See L<getpriority(2)>.) Will raise a fatal exception if used on a
machine that doesn't implement getpriority(2).
X<setnetent> X<setprotoent> X<setservent> X<endpwent> X<endgrent> X<endhostent>
X<endnetent> X<endprotoent> X<endservent>
+=for Pod::Functions get passwd record given user login name
+
=item getgrnam NAME
+=for Pod::Functions get group record given group name
+
=item gethostbyname NAME
+=for Pod::Functions get host record given name
+
=item getnetbyname NAME
+=for Pod::Functions get networks record given name
+
=item getprotobyname NAME
+=for Pod::Functions get protocol record given name
+
=item getpwuid UID
+=for Pod::Functions get passwd record given user ID
+
=item getgrgid GID
+=for Pod::Functions get group record given group user ID
+
=item getservbyname NAME,PROTO
+=for Pod::Functions get services record given its name
+
=item gethostbyaddr ADDR,ADDRTYPE
+=for Pod::Functions get host record given its address
+
=item getnetbyaddr ADDR,ADDRTYPE
+=for Pod::Functions get network record given its address
+
=item getprotobynumber NUMBER
+=for Pod::Functions get protocol record numeric protocol
+
=item getservbyport PORT,PROTO
+=for Pod::Functions get services record given numeric port
+
=item getpwent
+=for Pod::Functions get next passwd record
+
=item getgrent
+=for Pod::Functions get next group record
+
=item gethostent
+=for Pod::Functions get next hosts record
+
=item getnetent
+=for Pod::Functions get next networks record
+
=item getprotoent
+=for Pod::Functions get next protocols record
+
=item getservent
+=for Pod::Functions get next services record
+
=item setpwent
+=for Pod::Functions prepare passwd file for use
+
=item setgrent
+=for Pod::Functions prepare group file for use
+
=item sethostent STAYOPEN
+=for Pod::Functions prepare hosts file for use
+
=item setnetent STAYOPEN
+=for Pod::Functions prepare networks file for use
+
=item setprotoent STAYOPEN
+=for Pod::Functions prepare protocols file for use
+
=item setservent STAYOPEN
+=for Pod::Functions prepare services file for use
+
=item endpwent
+=for Pod::Functions be done using passwd file
+
=item endgrent
+=for Pod::Functions be done using group file
+
=item endhostent
+=for Pod::Functions be done using hosts file
+
=item endnetent
+=for Pod::Functions be done using networks file
+
=item endprotoent
+=for Pod::Functions be done using protocols file
+
=item endservent
+=for Pod::Functions be done using services file
+
These routines are the same as their counterparts in the
system C library. In list context, the return values from the
various get routines are as follows:
=item getsockname SOCKET
X<getsockname>
+=for Pod::Functions retrieve the sockaddr for a given socket
+
Returns the packed sockaddr address of this end of the SOCKET connection,
in case you don't know the address because you have several different
IPs that the connection might have come in on.
=item getsockopt SOCKET,LEVEL,OPTNAME
X<getsockopt>
+=for Pod::Functions get socket options on a given socket
+
Queries the option named OPTNAME associated with SOCKET at a given LEVEL.
Options may exist at multiple protocol levels depending on the socket
type, but at least the uppermost socket level SOL_SOCKET (defined in the
my $packed = getsockopt($socket, $tcp, TCP_NODELAY)
or die "getsockopt TCP_NODELAY: $!";
my $nodelay = unpack("I", $packed);
- print "Nagle's algorithm is turned ", $nodelay ? "off\n" : "on\n";
+ print "Nagle's algorithm is turned ",
+ $nodelay ? "off\n" : "on\n";
Portability issues: L<perlport/getsockopt>.
-=item given EXPR BLOCK
-X<given>
-
-=item given BLOCK
-
-C<given> is analogous to the C<switch>
-keyword in other languages. C<given>
-and C<when> are used in Perl to implement C<switch>/C<case> like statements.
-Only available after Perl 5.10. For example:
-
- use v5.10;
- given ($fruit) {
- when (/apples?/) {
- print "I like apples."
- }
- when (/oranges?/) {
- print "I don't like oranges."
- }
- default {
- print "I don't like anything"
- }
- }
-
-See L<perlsyn/"Switch Statements"> for detailed information.
-
=item glob EXPR
X<glob> X<wildcard> X<filename, expansion> X<expand>
=item glob
+=for Pod::Functions expand filenames using wildcards
+
In list context, returns a (possibly empty) list of filename expansions on
the value of EXPR such as the standard Unix shell F</bin/csh> would do. In
scalar context, glob iterates through such filename expansions, returning
@many = glob "{apple,tomato,cherry}={green,yellow,red}";
-Beginning with v5.6.0, this operator is implemented using the standard
+This operator is implemented using the standard
C<File::Glob> extension. See L<File::Glob> for details, including
C<bsd_glob> which does not treat whitespace as a pattern separator.
=item gmtime
+=for Pod::Functions convert UNIX time into record or string using Greenwich time
+
Works just like L</localtime> but the returned values are
localized for the standard Greenwich time zone.
=item goto &NAME
+=for Pod::Functions create spaghetti code
+
The C<goto-LABEL> form finds the statement labeled with LABEL and
resumes execution there. It can't be used to get out of a block or
subroutine given to C<sort>. It can be used to go almost anywhere
As shown in this example, C<goto-EXPR> is exempt from the "looks like a
function" rule. A pair of parentheses following it does not (necessarily)
delimit its argument. C<goto("NE")."XT"> is equivalent to C<goto NEXT>.
+Also, unlike most named operators, this has the same precedence as
+assignment.
Use of C<goto-LABEL> or C<goto-EXPR> to jump into a construct is
deprecated and will issue a warning. Even then, it may not be used to
=item grep EXPR,LIST
+=for Pod::Functions locate elements in a list test true against a given criterion
+
This is similar in spirit to, but not the same as, grep(1) and its
relatives. In particular, it is not limited to using regular expressions.
This is usually something to be avoided when writing clear code.
If C<$_> is lexical in the scope where the C<grep> appears (because it has
-been declared with C<my $_>) then, in addition to being locally aliased to
+been declared with the deprecated C<my $_> construct)
+then, in addition to being locally aliased to
the list elements, C<$_> keeps being lexical inside the block; i.e., it
can't be seen from the outside, avoiding any potential side-effects.
=item hex
+=for Pod::Functions convert a string to a hexadecimal number
+
Interprets EXPR as a hex string and returns the corresponding value.
(To convert strings that might start with either C<0>, C<0x>, or C<0b>, see
L</oct>.) If EXPR is omitted, uses C<$_>.
=item import LIST
X<import>
+=for Pod::Functions patch a module's namespace into your own
+
There is no builtin C<import> function. It is just an ordinary
method (subroutine) defined (or inherited) by modules that wish to export
names to another module. The C<use> function calls the C<import> method
=item index STR,SUBSTR
+=for Pod::Functions find a substring within a string
+
The index function searches for one string within another, but without
the wildcard-like behavior of a full regular-expression pattern match.
It returns the position of the first occurrence of SUBSTR in STR at
=item int
+=for Pod::Functions get the integer portion of a number
+
Returns the integer portion of EXPR. If EXPR is omitted, uses C<$_>.
You should not use this function for rounding: one because it truncates
towards C<0>, and two because machine representations of floating-point
=item ioctl FILEHANDLE,FUNCTION,SCALAR
X<ioctl>
+=for Pod::Functions system-dependent device control system call
+
Implements the ioctl(2) function. You'll probably first have to say
- require "sys/ioctl.ph"; # probably in $Config{archlib}/sys/ioctl.ph
+ require "sys/ioctl.ph"; # probably in
+ # $Config{archlib}/sys/ioctl.ph
to get the correct function definitions. If F<sys/ioctl.ph> doesn't
exist or doesn't have the correct definitions you'll have to roll your
=item join EXPR,LIST
X<join>
+=for Pod::Functions join a list into a string using a separator
+
Joins the separate strings of LIST into a single string with fields
separated by the value of EXPR, and returns that new string. Example:
=item keys EXPR
+=for Pod::Functions retrieve list of indices from a hash
+
Called in list context, returns a list consisting of all the keys of the
named hash, or in Perl 5.12 or later only, the indices of an array. Perl
releases prior to 5.12 will produce a syntax error if you try to use an
Perl for security reasons (see L<perlsec/"Algorithmic Complexity
Attacks">).
-As a side effect, calling keys() resets the internal interator of the HASH or ARRAY
-(see L</each>). In particular, calling keys() in void context resets
+As a side effect, calling keys() resets the internal iterator of the HASH or
+ARRAY (see L</each>). In particular, calling keys() in void context resets
the iterator with no other overhead.
Here is yet another way to print your environment:
=item kill SIGNAL
X<kill> X<signal>
+=for Pod::Functions send a signal to a process or process group
+
Sends a signal to a list of processes. Returns the number of
processes successfully signaled (which is not necessarily the
same as the number actually killed).
Unlike in the shell, if SIGNAL is negative, it kills process groups instead
of processes. That means you usually
want to use positive not negative signals.
-You may also use a signal name in quotes.
+
+You may also use a signal name in quotes. A negative signal name is the
+same as a negative signal number, killing process groups instead of processes.
+For example, C<kill -KILL, $pgrp> will send C<SIGKILL> to the entire process
+group specified.
The behavior of kill when a I<PROCESS> number is zero or negative depends on
the operating system. For example, on POSIX-conforming systems, zero will
-signal the current process group and -1 will signal all processes.
+signal the current process group, -1 will signal all processes, and any
+other negative PROCESS number will act as a negative signal number and
+kill the entire process group specified.
+
+If both the SIGNAL and the PROCESS are negative, the results are undefined.
+A warning may be produced in a future version.
See L<perlipc/"Signals"> for more details.
=item last LABEL
X<last> X<break>
+=item last EXPR
+
=item last
+=for Pod::Functions exit a block prematurely
+
The C<last> command is like the C<break> statement in C (as used in
loops); it immediately exits the loop in question. If the LABEL is
-omitted, the command refers to the innermost enclosing loop. The
+omitted, the command refers to the innermost enclosing
+loop. The C<last EXPR> form, available starting in Perl
+5.18.0, allows a label name to be computed at run time,
+and is otherwise identical to C<last LABEL>. The
C<continue> block, if any, is not executed:
LINE: while (<STDIN>) {
See also L</continue> for an illustration of how C<last>, C<next>, and
C<redo> work.
+Unlike most named operators, this has the same precedence as assignment.
+It is also exempt from the looks-like-a-function rule, so
+C<last ("foo")."bar"> will cause "bar" to be part of the argument to
+C<last>.
+
=item lc EXPR
X<lc> X<lowercase>
=item lc
+=for Pod::Functions return lower-case version of a string
+
Returns a lowercased version of EXPR. This is the internal function
implementing the C<\L> escape in double-quoted strings.
=item lcfirst
+=for Pod::Functions return a string with just the next letter in lower case
+
Returns the value of EXPR with the first character lowercased. This
is the internal function implementing the C<\l> escape in
double-quoted strings.
=item length
+=for Pod::Functions return the number of characters in a string
+
Returns the length in I<characters> of the value of EXPR. If EXPR is
omitted, returns the length of C<$_>. If EXPR is undefined, returns
C<undef>.
=item __LINE__
X<__LINE__>
+=for Pod::Functions the current source line number
+
A special token that compiles to the current line number.
=item link OLDFILE,NEWFILE
X<link>
+=for Pod::Functions create a hard link in the filesystem
+
Creates a new filename linked to the old filename. Returns true for
success, false otherwise.
=item listen SOCKET,QUEUESIZE
X<listen>
+=for Pod::Functions register your socket as a server
+
Does the same thing that the listen(2) system call does. Returns true if
it succeeded, false otherwise. See the example in
L<perlipc/"Sockets: Client/Server Communication">.
=item local EXPR
X<local>
+=for Pod::Functions create a temporary value for a global variable (dynamic scoping)
+
You really probably want to be using C<my> instead, because C<local> isn't
what most people think of as "local". See
L<perlsub/"Private Variables via my()"> for details.
=item localtime
+=for Pod::Functions convert UNIX time into record or string using local time
+
Converts a time as returned by the time function to a 9-element list
with the time analyzed for the local time zone. Typically used as
follows:
the range C<0..11>, with 0 indicating January and 11 indicating December.
This makes it easy to get a month name from a list:
- my @abbr = qw( Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec );
+ my @abbr = qw(Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec);
print "$abbr[$mon] $mday";
# $mon=9, $mday=18 gives "Oct 18"
=item lock THING
X<lock>
+=for Pod::Functions +5.005 get a thread lock on a variable, subroutine, or method
+
This function places an advisory lock on a shared variable or referenced
object contained in I<THING> until the lock goes out of scope.
=item log
+=for Pod::Functions retrieve the natural logarithm for a number
+
Returns the natural logarithm (base I<e>) of EXPR. If EXPR is omitted,
returns the log of C<$_>. To get the
log of another base, use basic algebra:
=item lstat
+=for Pod::Functions stat a symbolic link
+
Does the same thing as the C<stat> function (including setting the
special C<_> filehandle) but stats a symbolic link instead of the file
the symbolic link points to. If symbolic links are unimplemented on
=item m//
+=for Pod::Functions match a string with a regular expression pattern
+
The match operator. See L<perlop/"Regexp Quote-Like Operators">.
=item map BLOCK LIST
=item map EXPR,LIST
+=for Pod::Functions apply a change to a list to get back a new list with the changes
+
Evaluates the BLOCK or EXPR for each element of LIST (locally setting
C<$_> to each element) and returns the list value composed of the
results of each such evaluation. In scalar context, returns the
the original list for which the BLOCK or EXPR evaluates to true.
If C<$_> is lexical in the scope where the C<map> appears (because it has
-been declared with C<my $_>), then, in addition to being locally aliased to
+been declared with the deprecated C<my $_> construct),
+then, in addition to being locally aliased to
the list elements, C<$_> keeps being lexical inside the block; that is, it
can't be seen from the outside, avoiding any potential side-effects.
reported close to the C<}>, but you'll need to change something near the C<{>
such as using a unary C<+> to give Perl some help:
- %hash = map { "\L$_" => 1 } @array # perl guesses EXPR. wrong
- %hash = map { +"\L$_" => 1 } @array # perl guesses BLOCK. right
- %hash = map { ("\L$_" => 1) } @array # this also works
- %hash = map { lc($_) => 1 } @array # as does this.
- %hash = map +( lc($_) => 1 ), @array # this is EXPR and works!
+ %hash = map { "\L$_" => 1 } @array # perl guesses EXPR. wrong
+ %hash = map { +"\L$_" => 1 } @array # perl guesses BLOCK. right
+ %hash = map { ("\L$_" => 1) } @array # this also works
+ %hash = map { lc($_) => 1 } @array # as does this.
+ %hash = map +( lc($_) => 1 ), @array # this is EXPR and works!
- %hash = map ( lc($_), 1 ), @array # evaluates to (1, @array)
+ %hash = map ( lc($_), 1 ), @array # evaluates to (1, @array)
or to force an anon hash constructor use C<+{>:
- @hashes = map +{ lc($_) => 1 }, @array # EXPR, so needs comma at end
+ @hashes = map +{ lc($_) => 1 }, @array # EXPR, so needs
+ # comma at end
to get a list of anonymous hashes each with only one entry apiece.
=item mkdir
+=for Pod::Functions create a directory
+
Creates the directory specified by FILENAME, with permissions
specified by MASK (as modified by C<umask>). If it succeeds it
returns true; otherwise it returns false and sets C<$!> (errno).
=item msgctl ID,CMD,ARG
X<msgctl>
+=for Pod::Functions SysV IPC message control operations
+
Calls the System V IPC function msgctl(2). You'll probably have to say
use IPC::SysV;
=item msgget KEY,FLAGS
X<msgget>
+=for Pod::Functions get SysV IPC message queue
+
Calls the System V IPC function msgget(2). Returns the message queue
id, or C<undef> on error. See also
L<perlipc/"SysV IPC"> and the documentation for C<IPC::SysV> and
=item msgrcv ID,VAR,SIZE,TYPE,FLAGS
X<msgrcv>
+=for Pod::Functions receive a SysV IPC message from a message queue
+
Calls the System V IPC function msgrcv to receive a message from
message queue ID into variable VAR with a maximum message size of
SIZE. Note that when a message is received, the message type as a
=item msgsnd ID,MSG,FLAGS
X<msgsnd>
+=for Pod::Functions send a SysV IPC message to a message queue
+
Calls the System V IPC function msgsnd to send the message MSG to the
message queue ID. MSG must begin with the native long integer message
type, be followed by the length of the actual message, and then finally
=item my TYPE EXPR : ATTRS
+=for Pod::Functions declare and assign a local variable (lexical scoping)
+
A C<my> declares the listed variables to be local (lexically) to the
enclosing block, file, or C<eval>. If more than one value is listed,
the list must be placed in parentheses.
=item next LABEL
X<next> X<continue>
+=item next EXPR
+
=item next
+=for Pod::Functions iterate a block prematurely
+
The C<next> command is like the C<continue> statement in C; it starts
the next iteration of the loop:
Note that if there were a C<continue> block on the above, it would get
executed even on discarded lines. If LABEL is omitted, the command
-refers to the innermost enclosing loop.
+refers to the innermost enclosing loop. The C<next EXPR> form, available
+as of Perl 5.18.0, allows a label name to be computed at run time, being
+otherwise identical to C<next LABEL>.
C<next> cannot be used to exit a block which returns a value such as
C<eval {}>, C<sub {}>, or C<do {}>, and should not be used to exit
See also L</continue> for an illustration of how C<last>, C<next>, and
C<redo> work.
+Unlike most named operators, this has the same precedence as assignment.
+It is also exempt from the looks-like-a-function rule, so
+C<next ("foo")."bar"> will cause "bar" to be part of the argument to
+C<next>.
+
=item no MODULE VERSION LIST
X<no declarations>
X<unimporting>
=item no VERSION
+=for Pod::Functions unimport some module symbols or semantics at compile time
+
See the C<use> function, of which C<no> is the opposite.
=item oct EXPR
=item oct
+=for Pod::Functions convert a string to an octal number
+
Interprets EXPR as an octal string and returns the corresponding
value. (If EXPR happens to start off with C<0x>, interprets it as a
hex string. If EXPR starts off with C<0b>, it is interpreted as a
=item open FILEHANDLE
+=for Pod::Functions open a file, pipe, or descriptor
+
Opens the file whose filename is given by EXPR, and associates it with
FILEHANDLE.
to the temporary file first. You will need to seek() to do the
reading.
-Since v5.8.0, Perl has built using PerlIO by default. Unless you've
+Perl is built using PerlIO by default; Unless you've
changed this (such as building Perl with C<Configure -Uuseperlio>), you can
open filehandles directly to Perl scalars via:
# in-memory files
open(MEMORY, ">", \$var)
or die "Can't open memory file: $!";
- print MEMORY "foo!\n"; # output will appear in $var
+ print MEMORY "foo!\n"; # output will appear in $var
# process argument list of files along with any includes
$child_pid = open(FROM_KID, "-|") // die "can't fork: $!";
or
+
$child_pid = open(TO_KID, "|-") // die "can't fork: $!";
followed by
# am the parent:
# either write TO_KID or else read FROM_KID
...
- wait $child_pid;
+ waitpid $child_pid, 0;
} else {
# am the child; use STDIN/STDOUT normally
...
See L<perlipc/"Safe Pipe Opens"> for more examples of this.
-Beginning with v5.6.0, Perl will attempt to flush all files opened for
+Perl will attempt to flush all files opened for
output before any operation that may do a fork, but this may not be
supported on some platforms (see L<perlport>). To be safe, you may need
to set C<$|> ($AUTOFLUSH in English) or call the C<autoflush()> method
}
B<WARNING:> The previous example has a bug because the automatic
-close that happens when the refcount on C<handle> does not
+close that happens when the refcount on C<handle> reaches zero does not
properly detect and report failures. I<Always> close the handle
yourself and inspect the return value.
=item opendir DIRHANDLE,EXPR
X<opendir>
+=for Pod::Functions open a directory
+
Opens a directory named EXPR for processing by C<readdir>, C<telldir>,
C<seekdir>, C<rewinddir>, and C<closedir>. Returns true if successful.
DIRHANDLE may be an expression whose value can be used as an indirect
=item ord
+=for Pod::Functions find a character's numeric representation
+
Returns the numeric value of the first character of EXPR.
If EXPR is an empty string, returns 0. If EXPR is omitted, uses C<$_>.
(Note I<character>, not byte.)
=item our TYPE EXPR : ATTRS
-C<our> associates a simple name with a package variable in the current
-package for use within the current scope. When C<use strict 'vars'> is in
-effect, C<our> lets you use declared global variables without qualifying
-them with package names, within the lexical scope of the C<our> declaration.
-In this way C<our> differs from C<use vars>, which is package-scoped.
+=for Pod::Functions +5.6.0 declare and assign a package variable (lexical scoping)
-Unlike C<my> or C<state>, which allocates storage for a variable and
-associates a simple name with that storage for use within the current
-scope, C<our> associates a simple name with a package (read: global)
-variable in the current package, for use within the current lexical scope.
-In other words, C<our> has the same scoping rules as C<my> or C<state>, but
-does not necessarily create a variable.
+C<our> makes a lexical alias to a package variable of the same name in the current
+package for use within the current lexical scope.
+
+C<our> has the same scoping rules as C<my> or C<state>, but C<our> only
+declares an alias, whereas C<my> or C<state> both declare a variable name and
+allocate storage for that name within the current scope.
+
+This means that when C<use strict 'vars'> is in effect, C<our> lets you use
+a package variable without qualifying it with the package name, but only within
+the lexical scope of the C<our> declaration. In this way, C<our> differs from
+C<use vars>, which allows use of an unqualified name I<only> within the
+affected package, but across scopes.
If more than one value is listed, the list must be placed
in parentheses.
our $foo;
our($bar, $baz);
-An C<our> declaration declares a global variable that will be visible
+An C<our> declaration declares an alias for a package variable that will be visible
across its entire lexical scope, even across package boundaries. The
package in which the variable is entered is determined at the point
of the declaration, not at the point of use. This means the following
=item pack TEMPLATE,LIST
X<pack>
+=for Pod::Functions convert a list into a binary representation
+
Takes a LIST of values and converts it into a string using the rules
given by the TEMPLATE. The resulting string is the concatenation of
the converted values. Typically, each converted value looks
to force a particular byte-order on all components in that group,
including all its subgroups.
+=begin comment
+
+Larry recalls that the hex and bit string formats (H, h, B, b) were added to
+pack for processing data from NASA's Magellan probe. Magellan was in an
+elliptical orbit, using the antenna for the radar mapping when close to
+Venus and for communicating data back to Earth for the rest of the orbit.
+There were two transmission units, but one of these failed, and then the
+other developed a fault whereby it would randomly flip the sense of all the
+bits. It was easy to automatically detect complete records with the correct
+sense, and complete records with all the bits flipped. However, this didn't
+recover the records where the sense flipped midway. A colleague of Larry's
+was able to pretty much eyeball where the records flipped, so they wrote an
+editor named kybble (a pun on the dog food Kibbles 'n Bits) to enable him to
+manually correct the records and recover the data. For this purpose pack
+gained the hex and bit string format specifiers.
+
+git shows that they were added to perl 3.0 in patch #44 (Jan 1991, commit
+27e2fb84680b9cc1), but the patch description makes no mention of their
+addition, let alone the story behind them.
+
+=end comment
+
The following rules apply:
=over
an explicit repeat count for pack, the packed string is adjusted to that
length. For example:
- This code: gives this result:
-
- unpack("W/a", "\004Gurusamy") ("Guru")
- unpack("a3/A A*", "007 Bond J ") (" Bond", "J")
- unpack("a3 x2 /A A*", "007: Bond, J.") ("Bond, J", ".")
+ This code: gives this result:
+
+ unpack("W/a", "\004Gurusamy") ("Guru")
+ unpack("a3/A A*", "007 Bond J ") (" Bond", "J")
+ unpack("a3 x2 /A A*", "007: Bond, J.") ("Bond, J", ".")
- pack("n/a* w/a","hello,","world") "\000\006hello,\005world"
- pack("a/W2", ord("a") .. ord("z")) "2ab"
+ pack("n/a* w/a","hello,","world") "\000\006hello,\005world"
+ pack("a/W2", ord("a") .. ord("z")) "2ab"
The I<length-item> is not returned explicitly from C<unpack>.
=item *
-Starting with Perl 5.9.2, integer and floating-point formats, along with
+Starting with Perl 5.10.0, integer and floating-point formats, along with
the C<p> and C<P> formats and C<()> groups, may all be followed by the
C<< > >> or C<< < >> endianness modifiers to respectively enforce big-
or little-endian byte-order. These modifiers are especially useful
=item package NAMESPACE VERSION BLOCK
X<package> X<module> X<namespace> X<version>
+=for Pod::Functions declare a separate global namespace
+
Declares the BLOCK or the rest of the compilation unit as being in the
given namespace. The scope of the package declaration is either the
supplied code BLOCK or, in the absence of a BLOCK, from the declaration
like C<STDOUT>, C<ARGV>, C<ENV>, and the punctuation variables.
A package statement affects dynamic variables only, including those
-you've used C<local> on, but I<not> lexical variables, which are created
+you've used C<local> on, but I<not> lexically-scoped variables, which are created
with C<my>, C<state>, or C<our>. Typically it would be the first
declaration in a file included by C<require> or C<use>. You can switch into a
package in more than one place, since this only determines which default
See L<perlmod/"Packages"> for more information about packages, modules,
and classes. See L<perlsub> for other scoping issues.
+=item __PACKAGE__
+X<__PACKAGE__>
+
+=for Pod::Functions +5.004 the current package
+
+A special token that returns the name of the package in which it occurs.
+
=item pipe READHANDLE,WRITEHANDLE
X<pipe>
+=for Pod::Functions open a pair of connected filehandles
+
Opens a pair of connected pipes like the corresponding system call.
Note that if you set up a loop of piped processes, deadlock can occur
unless you are very careful. In addition, note that Perl's pipes use
IO buffering, so you may need to set C<$|> to flush your WRITEHANDLE
after each command, depending on the application.
+Returns true on success.
+
See L<IPC::Open2>, L<IPC::Open3>, and
L<perlipc/"Bidirectional Communication with Another Process">
for examples of such things.
on all newly opened file descriptors whose C<fileno>s are I<higher> than
the current value of $^F (by default 2 for C<STDERR>). See L<perlvar/$^F>.
-=item __PACKAGE__
-X<__PACKAGE__>
-
-A special token that returns the name of the package in which it occurs.
-
=item pop ARRAY
X<pop> X<stack>
=item pop
+=for Pod::Functions remove the last element from an array and return it
+
Pops and returns the last value of the array, shortening the array by
one element.
=item pos
+=for Pod::Functions find or set the offset for the last/next m//g search
+
Returns the offset of where the last C<m//g> search left off for the
variable in question (C<$_> is used when the variable is not
specified). Note that 0 is a valid match offset. C<undef> indicates
=item print
+=for Pod::Functions output a list to a filehandle
+
Prints a string or a list of strings. Returns true if successful.
FILEHANDLE may be a scalar variable containing the name of or a reference
to the filehandle, thus introducing one level of indirection. (NOTE: If
=item printf
+=for Pod::Functions output a formatted list to a filehandle
+
Equivalent to C<print FILEHANDLE sprintf(FORMAT, LIST)>, except that C<$\>
-(the output record separator) is not appended. The first argument of the
-list will be interpreted as the C<printf> format. See
+(the output record separator) is not appended. The FORMAT and the
+LIST are actually parsed as a single list. The first argument
+of the list will be interpreted as the C<printf> format. This
+means that C<printf(@_)> will use C<$_[0]> as the format. See
L<sprintf|/sprintf FORMAT, LIST> for an
-explanation of the format argument. If you omit the LIST, C<$_> is used;
-to use FILEHANDLE without a LIST, you must use a real filehandle like
-C<FH>, not an indirect one like C<$fh>. If C<use locale> (including
+explanation of the format argument. If C<use locale> (including
C<use locale ':not_characters'>) is in effect and
POSIX::setlocale() has been called, the character used for the decimal
separator in formatted floating-point numbers is affected by the LC_NUMERIC
locale setting. See L<perllocale> and L<POSIX>.
+For historical reasons, if you omit the list, C<$_> is used as the format;
+to use FILEHANDLE without a list, you must use a real filehandle like
+C<FH>, not an indirect one like C<$fh>. However, this will rarely do what
+you want; if $_ contains formatting codes, they will be replaced with the
+empty string and a warning will be emitted if warnings are enabled. Just
+use C<print> if you want to print the contents of $_.
+
Don't fall into the trap of using a C<printf> when a simple
C<print> would do. The C<print> is more efficient and less
error prone.
=item prototype FUNCTION
X<prototype>
+=for Pod::Functions +5.002 get the prototype (if any) of a subroutine
+
Returns the prototype of a function as a string (or C<undef> if the
function has no prototype). FUNCTION is a reference to, or the name of,
the function whose prototype you want to retrieve.
If FUNCTION is a string starting with C<CORE::>, the rest is taken as a
-name for a Perl builtin. If the builtin is not I<overridable> (such as
-C<qw//>) or if its arguments cannot be adequately expressed by a prototype
+name for a Perl builtin. If the builtin's arguments
+cannot be adequately expressed by a prototype
(such as C<system>), prototype() returns C<undef>, because the builtin
does not really behave like a Perl function. Otherwise, the string
describing the equivalent prototype is returned.
=item push EXPR,LIST
+=for Pod::Functions append one or more elements to an array
+
Treats ARRAY as a stack by appending the values of LIST to the end of
ARRAY. The length of ARRAY increases by the length of LIST. Has the same
effect as
=item q/STRING/
+=for Pod::Functions singly quote a string
+
=item qq/STRING/
-=item qx/STRING/
+=for Pod::Functions doubly quote a string
=item qw/STRING/
+=for Pod::Functions quote a list of words
+
+=item qx/STRING/
+
+=for Pod::Functions backquote quote a string
+
Generalized quotes. See L<perlop/"Quote-Like Operators">.
=item qr/STRING/
+=for Pod::Functions +5.005 compile pattern
+
Regexp-like quote. See L<perlop/"Regexp Quote-Like Operators">.
=item quotemeta EXPR
=item quotemeta
-Returns the value of EXPR with all non-"word"
-characters backslashed. (That is, all characters not matching
+=for Pod::Functions quote regular expression magic characters
+
+Returns the value of EXPR with all the ASCII non-"word"
+characters backslashed. (That is, all ASCII characters not matching
C</[A-Za-z_0-9]/> will be preceded by a backslash in the
returned string, regardless of any locale settings.)
This is the internal function implementing
the C<\Q> escape in double-quoted strings.
+(See below for the behavior on non-ASCII code points.)
If EXPR is omitted, uses C<$_>.
Normally, when accepting literal string
input from the user, quotemeta() or C<\Q> must be used.
-In Perl 5.14, all characters whose code points are above 127 are not
-quoted in UTF8-encoded strings, but all are quoted in UTF-8 strings.
-It is planned to change this behavior in 5.16, but the exact rules
-haven't been determined yet.
+In Perl v5.14, all non-ASCII characters are quoted in non-UTF-8-encoded
+strings, but not quoted in UTF-8 strings.
+
+Starting in Perl v5.16, Perl adopted a Unicode-defined strategy for
+quoting non-ASCII characters; the quoting of ASCII characters is
+unchanged.
+
+Also unchanged is the quoting of non-UTF-8 strings when outside the
+scope of a C<use feature 'unicode_strings'>, which is to quote all
+characters in the upper Latin1 range. This provides complete backwards
+compatibility for old programs which do not use Unicode. (Note that
+C<unicode_strings> is automatically enabled within the scope of a
+S<C<use v5.12>> or greater.)
+
+Within the scope of C<use locale>, all non-ASCII Latin1 code points
+are quoted whether the string is encoded as UTF-8 or not. As mentioned
+above, locale does not affect the quoting of ASCII-range characters.
+This protects against those locales where characters such as C<"|"> are
+considered to be word characters.
+
+Otherwise, Perl quotes non-ASCII characters using an adaptation from
+Unicode (see L<http://www.unicode.org/reports/tr31/>.)
+The only code points that are quoted are those that have any of the
+Unicode properties: Pattern_Syntax, Pattern_White_Space, White_Space,
+Default_Ignorable_Code_Point, or General_Category=Control.
+
+Of these properties, the two important ones are Pattern_Syntax and
+Pattern_White_Space. They have been set up by Unicode for exactly this
+purpose of deciding which characters in a regular expression pattern
+should be quoted. No character that can be in an identifier has these
+properties.
+
+Perl promises, that if we ever add regular expression pattern
+metacharacters to the dozen already defined
+(C<\ E<verbar> ( ) [ { ^ $ * + ? .>), that we will only use ones that have the
+Pattern_Syntax property. Perl also promises, that if we ever add
+characters that are considered to be white space in regular expressions
+(currently mostly affected by C</x>), they will all have the
+Pattern_White_Space property.
+
+Unicode promises that the set of code points that have these two
+properties will never change, so something that is not quoted in v5.16
+will never need to be quoted in any future Perl release. (Not all the
+code points that match Pattern_Syntax have actually had characters
+assigned to them; so there is room to grow, but they are quoted
+whether assigned or not. Perl, of course, would never use an
+unassigned code point as an actual metacharacter.)
+
+Quoting characters that have the other 3 properties is done to enhance
+the readability of the regular expression and not because they actually
+need to be quoted for regular expression purposes (characters with the
+White_Space property are likely to be indistinguishable on the page or
+screen from those with the Pattern_White_Space property; and the other
+two properties contain non-printing characters).
=item rand EXPR
X<rand> X<random>
=item rand
+=for Pod::Functions retrieve the next pseudorandom number
+
Returns a random fractional number greater than or equal to C<0> and less
than the value of EXPR. (EXPR should be positive.) If EXPR is
omitted, the value C<1> is used. Currently EXPR with the value C<0> is
=item read FILEHANDLE,SCALAR,LENGTH
+=for Pod::Functions fixed-length buffered input from a filehandle
+
Attempts to read LENGTH I<characters> of data into variable SCALAR
from the specified FILEHANDLE. Returns the number of characters
actually read, C<0> at end of file, or undef if there was an error (in
=item readdir DIRHANDLE
X<readdir>
+=for Pod::Functions get a directory from a directory handle
+
Returns the next directory entry for a directory opened by C<opendir>.
If used in list context, returns all the rest of the entries in the
directory. If there are no more entries, returns the undefined value in
@dots = grep { /^\./ && -f "$some_dir/$_" } readdir($dh);
closedir $dh;
-As of Perl 5.11.2 you can use a bare C<readdir> in a C<while> loop,
+As of Perl 5.12 you can use a bare C<readdir> in a C<while> loop,
which will set C<$_> on every iteration.
opendir(my $dh, $some_dir) || die;
=item readline
X<readline> X<gets> X<fgets>
+=for Pod::Functions fetch a record from a file
+
Reads from the filehandle whose typeglob is contained in EXPR (or from
C<*ARGV> if EXPR is not provided). In scalar context, each call reads and
returns the next line until end-of-file is reached, whereupon the
=item readlink
+=for Pod::Functions determine where a symbolic link is pointing
+
Returns the value of a symbolic link, if symbolic links are
implemented. If not, raises an exception. If there is a system
error, returns the undefined value and sets C<$!> (errno). If EXPR is
=item readpipe
X<readpipe>
+=for Pod::Functions execute a system command and collect standard output
+
EXPR is executed as a system command.
The collected standard output of the command is returned.
In scalar context, it comes back as a single (potentially
=item recv SOCKET,SCALAR,LENGTH,FLAGS
X<recv>
+=for Pod::Functions receive a message over a Socket
+
Receives a message on a socket. Attempts to receive LENGTH characters
of data into variable SCALAR from the specified SOCKET filehandle.
SCALAR will be grown or shrunk to the length actually read. Takes the
=item redo LABEL
X<redo>
+=item redo EXPR
+
=item redo
+=for Pod::Functions start this loop iteration over again
+
The C<redo> command restarts the loop block without evaluating the
conditional again. The C<continue> block, if any, is not executed. If
the LABEL is omitted, the command refers to the innermost enclosing
-loop. Programs that want to lie to themselves about what was just input
+loop. The C<redo EXPR> form, available starting in Perl 5.18.0, allows a
+label name to be computed at run time, and is otherwise identical to C<redo
+LABEL>. Programs that want to lie to themselves about what was just input
normally use this command:
# a simpleminded Pascal comment stripper
See also L</continue> for an illustration of how C<last>, C<next>, and
C<redo> work.
+Unlike most named operators, this has the same precedence as assignment.
+It is also exempt from the looks-like-a-function rule, so
+C<redo ("foo")."bar"> will cause "bar" to be part of the argument to
+C<redo>.
+
=item ref EXPR
X<ref> X<reference>
=item ref
+=for Pod::Functions find out the type of thing being referenced
+
Returns a non-empty string if EXPR is a reference, the empty
string otherwise. If EXPR
is not specified, C<$_> will be used. The value returned depends on the
=item rename OLDNAME,NEWNAME
X<rename> X<move> X<mv> X<ren>
+=for Pod::Functions change a filename
+
Changes the name of a file; an existing file NEWNAME will be
clobbered. Returns true for success, false otherwise.
=item require
+=for Pod::Functions load in external functions from a library at runtime
+
Demands a version of Perl specified by VERSION, or demands some semantics
specified by EXPR or by C<$_> if EXPR is not supplied.
require v5.6.1; # run time version check
require 5.6.1; # ditto
- require 5.006_001; # ditto; preferred for backwards compatibility
+ require 5.006_001; # ditto; preferred for backwards
+ compatibility
Otherwise, C<require> demands that a library file be included if it
hasn't already been included. The file is included via the do-FILE
=item reset
+=for Pod::Functions clear all variables of a given name
+
Generally used in a C<continue> block at the end of a loop to clear
variables and reset C<??> searches so that they work again. The
expression is interpreted as a list of single characters (hyphens
=item return
+=for Pod::Functions get out of a function early
+
Returns from a subroutine, C<eval>, or C<do FILE> with the value
given in EXPR. Evaluation of EXPR may be in list, scalar, or void
context, depending on how the return value will be used, and the context
or do FILE automatically returns the value of the last expression
evaluated.)
+Unlike most named operators, this is also exempt from the
+looks-like-a-function rule, so C<return ("foo")."bar"> will
+cause "bar" to be part of the argument to C<return>.
+
=item reverse LIST
X<reverse> X<rev> X<invert>
+=for Pod::Functions flip a string or a list
+
In list context, returns a list value consisting of the elements
of LIST in the opposite order. In scalar context, concatenates the
elements of LIST and returns a string value with all characters
Used without arguments in scalar context, reverse() reverses C<$_>.
$_ = "dlrow ,olleH";
- print reverse; # No output, list context
- print scalar reverse; # Hello, world
+ print reverse; # No output, list context
+ print scalar reverse; # Hello, world
Note that reversing an array to itself (as in C<@a = reverse @a>) will
-preserve non-existent elements whenever possible, i.e., for non magical
-arrays or tied arrays with C<EXISTS> and C<DELETE> methods.
+preserve non-existent elements whenever possible; i.e., for non-magical
+arrays or for tied arrays with C<EXISTS> and C<DELETE> methods.
This operator is also handy for inverting a hash, although there are some
caveats. If a value is duplicated in the original hash, only one of those
=item rewinddir DIRHANDLE
X<rewinddir>
+=for Pod::Functions reset directory handle
+
Sets the current position to the beginning of the directory for the
C<readdir> routine on DIRHANDLE.
=item rindex STR,SUBSTR
+=for Pod::Functions right-to-left substring search
+
Works just like index() except that it returns the position of the I<last>
occurrence of SUBSTR in STR. If POSITION is specified, returns the
last occurrence beginning at or before that position.
=item rmdir
+=for Pod::Functions remove a directory
+
Deletes the directory specified by FILENAME if that directory is
empty. If it succeeds it returns true; otherwise it returns false and
sets C<$!> (errno). If FILENAME is omitted, uses C<$_>.
=item s///
+=for Pod::Functions replace a pattern with a string
+
The substitution operator. See L<perlop/"Regexp Quote-Like Operators">.
=item say FILEHANDLE LIST
=item say
+=for Pod::Functions +say output a list to a filehandle, appending a newline
+
Just like C<print>, but implicitly appends a newline. C<say LIST> is
simply an abbreviation for C<{ local $\ = "\n"; print LIST }>. To use
FILEHANDLE without a LIST to print the contents of C<$_> to it, you must
=item scalar EXPR
X<scalar> X<context>
+=for Pod::Functions force a scalar context
+
Forces EXPR to be interpreted in scalar context and returns the value
of EXPR.
=item seek FILEHANDLE,POSITION,WHENCE
X<seek> X<fseek> X<filehandle, position>
+=for Pod::Functions reposition file pointer for random-access I/O
+
Sets FILEHANDLE's position, just like the C<fseek> call of C<stdio>.
FILEHANDLE may be an expression whose value gives the name of the
filehandle. The values for WHENCE are C<0> to set the new position
=item seekdir DIRHANDLE,POS
X<seekdir>
+=for Pod::Functions reposition directory pointer
+
Sets the current position for the C<readdir> routine on DIRHANDLE. POS
must be a value returned by C<telldir>. C<seekdir> also has the same caveats
about possible directory compaction as the corresponding system library
=item select
+=for Pod::Functions reset default output or do I/O multiplexing
+
Returns the currently selected filehandle. If FILEHANDLE is supplied,
sets the new current default filehandle for output. This has two
effects: first, a C<write> or a C<print> without a filehandle
=item semctl ID,SEMNUM,CMD,ARG
X<semctl>
+=for Pod::Functions SysV semaphore control operations
+
Calls the System V IPC function semctl(2). You'll probably have to say
use IPC::SysV;
=item semget KEY,NSEMS,FLAGS
X<semget>
+=for Pod::Functions get set of SysV semaphores
+
Calls the System V IPC function semget(2). Returns the semaphore id, or
the undefined value on error. See also
L<perlipc/"SysV IPC">, C<IPC::SysV>, C<IPC::SysV::Semaphore>
=item semop KEY,OPSTRING
X<semop>
+=for Pod::Functions SysV semaphore operations
+
Calls the System V IPC function semop(2) for semaphore operations
such as signalling and waiting. OPSTRING must be a packed array of
semop structures. Each semop structure can be generated with
=item send SOCKET,MSG,FLAGS
+=for Pod::Functions send a message over a socket
+
Sends a message on a socket. Attempts to send the scalar MSG to the SOCKET
filehandle. Takes the same flags as the system call of the same name. On
unconnected sockets, you must specify a destination to I<send to>, in which
=item setpgrp PID,PGRP
X<setpgrp> X<group>
+=for Pod::Functions set the process group of a process
+
Sets the current process group for the specified PID, C<0> for the current
process. Raises an exception when used on a machine that doesn't
implement POSIX setpgid(2) or BSD setpgrp(2). If the arguments are omitted,
=item setpriority WHICH,WHO,PRIORITY
X<setpriority> X<priority> X<nice> X<renice>
+=for Pod::Functions set a process's nice value
+
Sets the current priority for a process, a process group, or a user.
(See setpriority(2).) Raises an exception when used on a machine
that doesn't implement setpriority(2).
=item setsockopt SOCKET,LEVEL,OPTNAME,OPTVAL
X<setsockopt>
+=for Pod::Functions set some socket options
+
Sets the socket option requested. Returns C<undef> on error.
Use integer constants provided by the C<Socket> module for
LEVEL and OPNAME. Values for LEVEL can also be obtained from
=item shift
+=for Pod::Functions remove the first element of an array, and return it
+
Shifts the first value of the array off and returns it, shortening the
array by 1 and moving everything down. If there are no elements in the
array, returns the undefined value. If ARRAY is omitted, shifts the
=item shmctl ID,CMD,ARG
X<shmctl>
+=for Pod::Functions SysV shared memory operations
+
Calls the System V IPC function shmctl. You'll probably have to say
use IPC::SysV;
=item shmget KEY,SIZE,FLAGS
X<shmget>
+=for Pod::Functions get SysV shared memory segment identifier
+
Calls the System V IPC function shmget. Returns the shared memory
segment id, or C<undef> on error.
See also L<perlipc/"SysV IPC"> and C<IPC::SysV> documentation.
X<shmread>
X<shmwrite>
+=for Pod::Functions read SysV shared memory
+
=item shmwrite ID,STRING,POS,SIZE
+=for Pod::Functions write SysV shared memory
+
Reads or writes the System V shared memory segment ID starting at
position POS for size SIZE by attaching to it, copying in/out, and
detaching from it. When reading, VAR must be a variable that will
=item shutdown SOCKET,HOW
X<shutdown>
+=for Pod::Functions close down just half of a socket connection
+
Shuts down a socket connection in the manner indicated by HOW, which
has the same interpretation as in the syscall of the same name.
=item sin
+=for Pod::Functions return the sine of a number
+
Returns the sine of EXPR (expressed in radians). If EXPR is omitted,
returns sine of C<$_>.
=item sleep
+=for Pod::Functions block for some number of seconds
+
Causes the script to sleep for (integer) EXPR seconds, or forever if no
argument is given. Returns the integer number of seconds actually slept.
=item socket SOCKET,DOMAIN,TYPE,PROTOCOL
X<socket>
+=for Pod::Functions create a socket
+
Opens a socket of the specified kind and attaches it to filehandle
SOCKET. DOMAIN, TYPE, and PROTOCOL are specified the same as for
the syscall of the same name. You should C<use Socket> first
=item socketpair SOCKET1,SOCKET2,DOMAIN,TYPE,PROTOCOL
X<socketpair>
+=for Pod::Functions create a pair of sockets
+
Creates an unnamed pair of sockets in the specified domain, of the
specified type. DOMAIN, TYPE, and PROTOCOL are specified the same as
for the syscall of the same name. If unimplemented, raises an exception.
=item sort LIST
+=for Pod::Functions sort a list of values
+
In list context, this sorts the LIST and returns the sorted list value.
In scalar context, the behaviour of C<sort()> is undefined.
# sort lexically
@articles = sort @files;
-
+
# same thing, but with explicit sort routine
@articles = sort {$a cmp $b} @files;
-
+
# now case-insensitively
@articles = sort {fc($a) cmp fc($b)} @files;
-
+
# same thing in reversed order
@articles = sort {$b cmp $a} @files;
-
+
# sort numerically ascending
@articles = sort {$a <=> $b} @files;
-
+
# sort numerically descending
@articles = sort {$b <=> $a} @files;
-
+
# this sorts the %age hash by value instead of key
# using an in-line function
@eldest = sort { $age{$b} <=> $age{$a} } keys %age;
-
+
# sort using explicit subroutine name
sub byage {
$age{$a} <=> $age{$b}; # presuming numeric
}
@sortedclass = sort byage @class;
-
+
sub backwards { $b cmp $a }
@harry = qw(dog cat x Cain Abel);
@george = qw(gone chased yz Punished Axed);
# using a prototype allows you to use any comparison subroutine
# as a sort subroutine (including other package's subroutines)
package other;
- sub backwards ($$) { $_[1] cmp $_[0]; } # $a and $b are not set here
-
+ sub backwards ($$) { $_[1] cmp $_[0]; } # $a and $b are
+ # not set here
package main;
@new = sort other::backwards @old;
-
+
# guarantee stability, regardless of algorithm
use sort 'stable';
@new = sort { substr($a, 3, 5) cmp substr($b, 3, 5) } @old;
-
+
# force use of mergesort (not portable outside Perl 5.8)
use sort '_mergesort'; # note discouraging _
@new = sort { substr($a, 3, 5) cmp substr($b, 3, 5) } @old;
=item splice ARRAY or EXPR
+=for Pod::Functions add or remove elements anywhere in an array
+
Removes the elements designated by OFFSET and LENGTH from an array, and
replaces them with the elements of LIST, if any. In list context,
returns the elements removed from the array. In scalar context,
=item split
+=for Pod::Functions split up a string using a regexp delimiter
+
Splits the string EXPR into a list of strings and returns the
list in list context, or the size of the list in scalar context.
into more fields than necessary. Thus, when assigning to a list,
if LIMIT is omitted (or zero), then LIMIT is treated as though it
were one larger than the number of variables in the list; for the
-following, LIMIT is implicitly 4:
+following, LIMIT is implicitly 3:
- ($login, $passwd, $remainder) = split(/:/);
+ ($login, $passwd) = split(/:/);
Note that splitting an EXPR that evaluates to the empty string always
produces zero fields, regardless of the LIMIT specified.
=item sprintf FORMAT, LIST
X<sprintf>
+=for Pod::Functions formatted print into a string
+
Returns a string formatted by the usual C<printf> conventions of the C
library function C<sprintf>. See below for more details
and see L<sprintf(3)> or L<printf(3)> on your system for an explanation of
You can also explicitly specify the argument number to use for
the join string using something like C<*2$v>; for example:
- printf '%*4$vX %*4$vX %*4$vX', @addr[1..3], ":"; # 3 IPv6 addresses
+ printf '%*4$vX %*4$vX %*4$vX', # 3 IPv6 addresses
+ @addr[1..3], ":";
=item (minimum) width
a number here, or get the width from the next argument (with C<*>)
or from a specified argument (e.g., with C<*2$>):
-
printf "<%s>", "a"; # prints "<a>"
- printf "<%6s>", "a"; # prints "< a>"
- printf "<%*s>", 6, "a"; # prints "< a>"
- printf "<%*2$s>", "a", 6; # prints "< a>"
- printf "<%2s>", "long"; # prints "<long>" (does not truncate)
+ printf "<%s>", "a"; # prints "<a>"
+ printf "<%6s>", "a"; # prints "< a>"
+ printf "<%*s>", 6, "a"; # prints "< a>"
+ printf '<%*2$s>', "a", 6; # prints "< a>"
+ printf "<%2s>", "long"; # prints "<long>" (does not truncate)
If a field width obtained through C<*> is negative, it has the same
effect as the C<-> flag: left-justification.
but it is intended that this will be possible in the future, for
example using C<.*2$>:
- printf "<%.*2$x>", 1, 6; # INVALID, but in future will print "<000001>"
+ printf '<%.*2$x>', 1, 6; # INVALID, but in future will print
+ # "<000001>"
=item size
bits), but you can override this to use instead one of the standard C types,
as supported by the compiler used to build Perl:
- hh interpret integer as C type "char" or "unsigned char"
- on Perl 5.14 or later
- h interpret integer as C type "short" or "unsigned short"
- j interpret integer as C type "intmax_t" on Perl 5.14
- or later, and only with a C99 compiler (unportable)
- l interpret integer as C type "long" or "unsigned long"
- q, L, or ll interpret integer as C type "long long", "unsigned long long",
- or "quad" (typically 64-bit integers)
- t interpret integer as C type "ptrdiff_t" on Perl 5.14 or later
- z interpret integer as C type "size_t" on Perl 5.14 or later
+ hh interpret integer as C type "char" or "unsigned
+ char" on Perl 5.14 or later
+ h interpret integer as C type "short" or
+ "unsigned short"
+ j interpret integer as C type "intmax_t" on Perl
+ 5.14 or later, and only with a C99 compiler
+ (unportable)
+ l interpret integer as C type "long" or
+ "unsigned long"
+ q, L, or ll interpret integer as C type "long long",
+ "unsigned long long", or "quad" (typically
+ 64-bit integers)
+ t interpret integer as C type "ptrdiff_t" on Perl
+ 5.14 or later
+ z interpret integer as C type "size_t" on Perl 5.14
+ or later
As of 5.14, none of these raises an exception if they are not supported on
your platform. However, if warnings are enabled, a warning of the
You can find out whether your Perl supports quads via L<Config>:
use Config;
- if ($Config{use64bitint} eq "define" || $Config{longsize} >= 8) {
+ if ($Config{use64bitint} eq "define"
+ || $Config{longsize} >= 8) {
print "Nice quads!\n";
}
use Config;
if ($Config{uselongdouble} eq "define") {
- print "long doubles by default\n";
+ print "long doubles by default\n";
}
It can also be that long doubles and doubles are the same thing:
uses C<$a> for the width, C<$b> for the precision, and C<$c>
as the value to format; while:
- printf "<%*1$.*s>", $a, $b;
+ printf '<%*1$.*s>', $a, $b;
would use C<$a> for the width and precision, and C<$b> as the
value to format.
Here are some more examples; be aware that when using an explicit
index, the C<$> may need escaping:
- printf "%2\$d %d\n", 12, 34; # will print "34 12\n"
- printf "%2\$d %d %d\n", 12, 34; # will print "34 12 34\n"
- printf "%3\$d %d %d\n", 12, 34, 56; # will print "56 12 34\n"
- printf "%2\$*3\$d %d\n", 12, 34, 3; # will print " 34 12\n"
+ printf "%2\$d %d\n", 12, 34; # will print "34 12\n"
+ printf "%2\$d %d %d\n", 12, 34; # will print "34 12 34\n"
+ printf "%3\$d %d %d\n", 12, 34, 56; # will print "56 12 34\n"
+ printf "%2\$*3\$d %d\n", 12, 34, 3; # will print " 34 12\n"
=back
=item sqrt
+=for Pod::Functions square root function
+
Return the positive square root of EXPR. If EXPR is omitted, uses
C<$_>. Works only for non-negative operands unless you've
loaded the C<Math::Complex> module.
=item srand
+=for Pod::Functions seed the random number generator
+
Sets and returns the random number seed for the C<rand> operator.
The point of the function is to "seed" the C<rand> function so that C<rand>
use 5.014; # so srand returns the seed
If C<srand()> is not called explicitly, it is called implicitly without a
-parameter at the first use of the C<rand> operator. However, this was not true
-of versions of Perl before 5.004, so if your script will run under older
-Perl versions, it should call C<srand>; otherwise most programs won't call
-C<srand()> at all.
-
-But there are a few situations in recent Perls where programs are likely to
-want to call C<srand>. One is for generating predictable results generally for
+parameter at the first use of the C<rand> operator.
+However, there are a few situations where programs are likely to
+want to call C<srand>. One is for generating predictable results, generally for
testing or debugging. There, you use C<srand($seed)>, with the same C<$seed>
each time. Another case is that you may want to call C<srand()>
after a C<fork()> to avoid child processes sharing the same seed value as the
produce the same results as C<srand(42.1)>. To be safe, always pass
C<srand> an integer.
-In versions of Perl prior to 5.004 the default seed was just the
-current C<time>. This isn't a particularly good seed, so many old
-programs supply their own seed value (often C<time ^ $$> or C<time ^
-($$ + ($$ << 15))>), but that isn't necessary any more.
-
-Frequently called programs (like CGI scripts) that simply use
-
- time ^ $$
-
-for a seed can fall prey to the mathematical property that
-
- a^b == (a+1)^(b+1)
-
-one-third of the time. So don't do that.
-
A typical use of the returned seed is for a test program which has too many
combinations to test comprehensively in the time available to it each run. It
can test a random subset each time, and should there be a failure, log the seed
=item stat
+=for Pod::Functions get a file's status information
+
Returns a 13-element list giving the status info for a file, either
the file opened via FILEHANDLE or DIRHANDLE, or named by EXPR. If EXPR is
omitted, it stats C<$_> (not C<_>!). Returns the empty list if C<stat> fails. Typically
8 atime last access time in seconds since the epoch
9 mtime last modify time in seconds since the epoch
10 ctime inode change time in seconds since the epoch (*)
- 11 blksize preferred block size for file system I/O
- 12 blocks actual number of blocks allocated
+ 11 blksize preferred I/O size in bytes for interacting with the
+ file (may vary from file to file)
+ 12 blocks actual number of system-specific blocks allocated
+ on disk (often, but not always, 512 bytes each)
(The epoch was at 00:00 January 1, 1970 GMT.)
=item state TYPE EXPR : ATTRS
+=for Pod::Functions +state declare and assign a persistent lexical variable
+
C<state> declares a lexically scoped variable, just like C<my>.
However, those variables will never be reinitialized, contrary to
lexical variables that are reinitialized each time their enclosing block
=item study
+=for Pod::Functions optimize input data for repeated searches
+
Takes extra time to study SCALAR (C<$_> if unspecified) in anticipation of
doing many pattern matches on the string before it is next modified.
This may or may not save time, depending on the nature and number of
=item sub NAME (PROTO) : ATTRS BLOCK
+=for Pod::Functions declare a subroutine, possibly anonymously
+
This is subroutine definition, not a real function I<per se>. Without a
BLOCK it's just a forward declaration. Without a NAME, it's an anonymous
function declaration, so does return a value: the CODE ref of the closure
=item __SUB__
X<__SUB__>
+=for Pod::Functions +current_sub the current subroutine, or C<undef> if not in a subroutine
+
A special token that returns the a reference to the current subroutine, or
C<undef> outside of a subroutine.
=item substr EXPR,OFFSET
+=for Pod::Functions get or alter a portion of a string
+
Extracts a substring out of EXPR and returns it. First character is at
offset zero. If OFFSET is negative, starts
that far back from the end of the string. If LENGTH is omitted, returns
=item symlink OLDFILE,NEWFILE
X<symlink> X<link> X<symbolic link> X<link, symbolic>
+=for Pod::Functions create a symbolic link to a file
+
Creates a new filename symbolically linked to the old filename.
Returns C<1> for success, C<0> otherwise. On systems that don't support
symbolic links, raises an exception. To check for that,
=item syscall NUMBER, LIST
X<syscall> X<system call>
+=for Pod::Functions execute an arbitrary system call
+
Calls the system call specified as the first element of the list,
passing the remaining elements as arguments to the system call. If
unimplemented, raises an exception. The arguments are interpreted
=item sysopen FILEHANDLE,FILENAME,MODE,PERMS
+=for Pod::Functions +5.002 open a file, pipe, or descriptor
+
Opens the file whose filename is given by FILENAME, and associates it with
FILEHANDLE. If FILEHANDLE is an expression, its value is used as the real
filehandle wanted; an undefined scalar will be suitably autovivified. This
For historical reasons, some values work on almost every system
supported by Perl: 0 means read-only, 1 means write-only, and 2
means read/write. We know that these values do I<not> work under
-OS/390 & VM/ESA Unix and on the Macintosh; you probably don't want to
+OS/390 and on the Macintosh; you probably don't want to
use them in new code.
If the file named by FILENAME does not exist and the C<open> call creates
=item sysread FILEHANDLE,SCALAR,LENGTH
+=for Pod::Functions fixed-length unbuffered input from a filehandle
+
Attempts to read LENGTH bytes of data into variable SCALAR from the
specified FILEHANDLE, using the read(2). It bypasses
buffered IO, so mixing this with other kinds of reads, C<print>,
=item sysseek FILEHANDLE,POSITION,WHENCE
X<sysseek> X<lseek>
+=for Pod::Functions +5.004 position I/O pointer on handle used with sysread and syswrite
+
Sets FILEHANDLE's system position in bytes using lseek(2). FILEHANDLE may
be an expression whose value gives the name of the filehandle. The values
for WHENCE are C<0> to set the new position to POSITION; C<1> to set the it
=item system PROGRAM LIST
+=for Pod::Functions run a separate program
+
Does exactly the same thing as C<exec LIST>, except that a fork is
done first and the parent process waits for the child process to
exit. Note that argument processing varies depending on the
it is split into words and passed directly to C<execvp>, which is
more efficient.
-Beginning with v5.6.0, Perl will attempt to flush all files opened for
+Perl will attempt to flush all files opened for
output before any operation that may do a fork, but this may not be
supported on some platforms (see L<perlport>). To be safe, you may need
to set C<$|> ($AUTOFLUSH in English) or call the C<autoflush()> method
=item syswrite FILEHANDLE,SCALAR
+=for Pod::Functions fixed-length unbuffered output to a filehandle
+
Attempts to write LENGTH bytes of data from variable SCALAR to the
specified FILEHANDLE, using write(2). If LENGTH is
not specified, writes whole SCALAR. It bypasses buffered IO, so
=item tell
+=for Pod::Functions get current seekpointer on a filehandle
+
Returns the current position I<in bytes> for FILEHANDLE, or -1 on
error. FILEHANDLE may be an expression whose value gives the name of
the actual filehandle. If FILEHANDLE is omitted, assumes the file
=item telldir DIRHANDLE
X<telldir>
+=for Pod::Functions get current seekpointer on a directory handle
+
Returns the current position of the C<readdir> routines on DIRHANDLE.
Value may be given to C<seekdir> to access a particular location in a
directory. C<telldir> has the same caveats about possible directory
=item tie VARIABLE,CLASSNAME,LIST
X<tie>
+=for Pod::Functions +5.002 bind a variable to an object class
+
This function binds a variable to a package class that will provide the
implementation for the variable. VARIABLE is the name of the variable
to be enchanted. CLASSNAME is the name of a class implementing objects
=item tied VARIABLE
X<tied>
+=for Pod::Functions get a reference to the object underlying a tied variable
+
Returns a reference to the object underlying VARIABLE (the same value
that was originally returned by the C<tie> call that bound the variable
to a package.) Returns the undefined value if VARIABLE isn't tied to a
=item time
X<time> X<epoch>
+=for Pod::Functions return number of seconds since 1970
+
Returns the number of non-leap seconds since whatever time the system
considers to be the epoch, suitable for feeding to C<gmtime> and
C<localtime>. On most systems the epoch is 00:00:00 UTC, January 1, 1970;
=item times
X<times>
+=for Pod::Functions return elapsed time for self and child processes
+
Returns a four-element list giving the user and system times in
seconds for this process and any exited children of this process.
=item tr///
+=for Pod::Functions transliterate a string
+
The transliteration operator. Same as C<y///>. See
L<perlop/"Quote and Quote-like Operators">.
=item truncate EXPR,LENGTH
+=for Pod::Functions shorten a file
+
Truncates the file opened on FILEHANDLE, or named by EXPR, to the
specified length. Raises an exception if truncate isn't implemented
on your system. Returns true if successful, C<undef> on error.
=item uc
+=for Pod::Functions return upper-case version of a string
+
Returns an uppercased version of EXPR. This is the internal function
implementing the C<\U> escape in double-quoted strings.
It does not attempt to do titlecase mapping on initial letters. See
=item ucfirst
+=for Pod::Functions return a string with just the next letter in upper case
+
Returns the value of EXPR with the first character in uppercase
(titlecase in Unicode). This is the internal function implementing
the C<\u> escape in double-quoted strings.
=item umask
+=for Pod::Functions set file creation mode mask
+
Sets the umask for the process to EXPR and returns the previous value.
If EXPR is omitted, merely returns the current umask.
=item undef
+=for Pod::Functions remove a variable or function definition
+
Undefines the value of EXPR, which must be an lvalue. Use only on a
scalar value, an array (using C<@>), a hash (using C<%>), a subroutine
(using C<&>), or a typeglob (using C<*>). Saying C<undef $hash{$key}>
=item unlink
+=for Pod::Functions remove one link to a file
+
Deletes a list of files. On success, it returns the number of files
it successfully deleted. On failure, it returns false and sets C<$!>
(errno):
=item unpack TEMPLATE
+=for Pod::Functions convert binary structure into normal perl variables
+
C<unpack> does the reverse of C<pack>: it takes a string
and expands it out into a list of values.
(In scalar context, it returns merely the first value produced.)
=item unshift EXPR,LIST
+=for Pod::Functions prepend more elements to the beginning of a list
+
Does the opposite of a C<shift>. Or the opposite of a C<push>,
depending on how you look at it. Prepends list to the front of the
array and returns the new number of elements in the array.
=item untie VARIABLE
X<untie>
+=for Pod::Functions break a tie binding to a variable
+
Breaks the binding between a variable and a package.
(See L<tie|/tie VARIABLE,CLASSNAME,LIST>.)
Has no effect if the variable is not tied.
=item use VERSION
+=for Pod::Functions load in a module at compile time and import its namespace
+
Imports some semantics into the current package from the named module,
generally by aliasing certain subroutine or variable names into your
package. It is exactly equivalent to
BEGIN { require Module; Module->import( LIST ); }
except that Module I<must> be a bareword.
-The importation can be made conditional; see L<if>.
+The importation can be made conditional by using the L<if> module.
In the peculiar C<use VERSION> form, VERSION may be either a positive
decimal fraction such as 5.006, which will be compared to C<$]>, or a v-string
C<use VERSION> also enables all features available in the requested
version as defined by the C<feature> pragma, disabling any features
-not in the current version's feature bundle. See L<feature>.
+not in the requested version's feature bundle. See L<feature>.
Similarly, if the specified Perl version is greater than or equal to
-5.11.0, strictures are enabled lexically as
+5.12.0, strictures are enabled lexically as
with C<use strict>. Any explicit use of
C<use strict> or C<no strict> overrides C<use VERSION>, even if it comes
before it. In both cases, the F<feature.pm> and F<strict.pm> files are
=item utime LIST
X<utime>
+=for Pod::Functions set a file's last access and modify times
+
Changes the access and modification times on each file of a list of
files. The first two elements of the list must be the NUMERIC access
and modification times, in that order. Returns the number of files
$atime = $mtime = time;
utime $atime, $mtime, @ARGV;
-Since Perl 5.7.2, if the first two elements of the list are C<undef>,
+Since Perl 5.8.0, if the first two elements of the list are C<undef>,
the utime(2) syscall from your C library is called with a null second
argument. On most systems, this will set the file's access and
modification times to the current time (i.e., equivalent to the example
=item values EXPR
+=for Pod::Functions return a list of the values in a hash
+
In list context, returns a list consisting of all the values of the named
hash. In Perl 5.12 or later only, will also return a list of the values of
an array; prior to that release, attempting to use an array argument will
Note that the values are not copied, which means modifying them will
modify the contents of the hash:
- for (values %hash) { s/foo/bar/g } # modifies %hash values
- for (@hash{keys %hash}) { s/foo/bar/g } # same
+ for (values %hash) { s/foo/bar/g } # modifies %hash values
+ for (@hash{keys %hash}) { s/foo/bar/g } # same
Starting with Perl 5.14, C<values> can take a scalar EXPR, which must hold
a reference to an unblessed hash or array. The argument will be
=item vec EXPR,OFFSET,BITS
X<vec> X<bit> X<bit vector>
+=for Pod::Functions test or set particular bits in a string
+
Treats the string in EXPR as a bit vector made up of elements of
width BITS and returns the value of the element specified by OFFSET
as an unsigned integer. BITS therefore specifies the number of bits
Here is an example to illustrate how the bits actually fall in place:
- #!/usr/bin/perl -wl
-
- print <<'EOT';
- 0 1 2 3
- unpack("V",$_) 01234567890123456789012345678901
- ------------------------------------------------------------------
- EOT
-
- for $w (0..3) {
- $width = 2**$w;
- for ($shift=0; $shift < $width; ++$shift) {
- for ($off=0; $off < 32/$width; ++$off) {
- $str = pack("B*", "0"x32);
- $bits = (1<<$shift);
- vec($str, $off, $width) = $bits;
- $res = unpack("b*",$str);
- $val = unpack("V", $str);
- write;
- }
- }
- }
-
- format STDOUT =
- vec($_,@#,@#) = @<< == @######### @>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
- $off, $width, $bits, $val, $res
- .
- __END__
+ #!/usr/bin/perl -wl
+
+ print <<'EOT';
+ 0 1 2 3
+ unpack("V",$_) 01234567890123456789012345678901
+ ------------------------------------------------------------------
+ EOT
+
+ for $w (0..3) {
+ $width = 2**$w;
+ for ($shift=0; $shift < $width; ++$shift) {
+ for ($off=0; $off < 32/$width; ++$off) {
+ $str = pack("B*", "0"x32);
+ $bits = (1<<$shift);
+ vec($str, $off, $width) = $bits;
+ $res = unpack("b*",$str);
+ $val = unpack("V", $str);
+ write;
+ }
+ }
+ }
+
+ format STDOUT =
+ vec($_,@#,@#) = @<< == @######### @>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
+ $off, $width, $bits, $val, $res
+ .
+ __END__
Regardless of the machine architecture on which it runs, the
example above should print the following table:
- 0 1 2 3
- unpack("V",$_) 01234567890123456789012345678901
- ------------------------------------------------------------------
- vec($_, 0, 1) = 1 == 1 10000000000000000000000000000000
- vec($_, 1, 1) = 1 == 2 01000000000000000000000000000000
- vec($_, 2, 1) = 1 == 4 00100000000000000000000000000000
- vec($_, 3, 1) = 1 == 8 00010000000000000000000000000000
- vec($_, 4, 1) = 1 == 16 00001000000000000000000000000000
- vec($_, 5, 1) = 1 == 32 00000100000000000000000000000000
- vec($_, 6, 1) = 1 == 64 00000010000000000000000000000000
- vec($_, 7, 1) = 1 == 128 00000001000000000000000000000000
- vec($_, 8, 1) = 1 == 256 00000000100000000000000000000000
- vec($_, 9, 1) = 1 == 512 00000000010000000000000000000000
- vec($_,10, 1) = 1 == 1024 00000000001000000000000000000000
- vec($_,11, 1) = 1 == 2048 00000000000100000000000000000000
- vec($_,12, 1) = 1 == 4096 00000000000010000000000000000000
- vec($_,13, 1) = 1 == 8192 00000000000001000000000000000000
- vec($_,14, 1) = 1 == 16384 00000000000000100000000000000000
- vec($_,15, 1) = 1 == 32768 00000000000000010000000000000000
- vec($_,16, 1) = 1 == 65536 00000000000000001000000000000000
- vec($_,17, 1) = 1 == 131072 00000000000000000100000000000000
- vec($_,18, 1) = 1 == 262144 00000000000000000010000000000000
- vec($_,19, 1) = 1 == 524288 00000000000000000001000000000000
- vec($_,20, 1) = 1 == 1048576 00000000000000000000100000000000
- vec($_,21, 1) = 1 == 2097152 00000000000000000000010000000000
- vec($_,22, 1) = 1 == 4194304 00000000000000000000001000000000
- vec($_,23, 1) = 1 == 8388608 00000000000000000000000100000000
- vec($_,24, 1) = 1 == 16777216 00000000000000000000000010000000
- vec($_,25, 1) = 1 == 33554432 00000000000000000000000001000000
- vec($_,26, 1) = 1 == 67108864 00000000000000000000000000100000
- vec($_,27, 1) = 1 == 134217728 00000000000000000000000000010000
- vec($_,28, 1) = 1 == 268435456 00000000000000000000000000001000
- vec($_,29, 1) = 1 == 536870912 00000000000000000000000000000100
- vec($_,30, 1) = 1 == 1073741824 00000000000000000000000000000010
- vec($_,31, 1) = 1 == 2147483648 00000000000000000000000000000001
- vec($_, 0, 2) = 1 == 1 10000000000000000000000000000000
- vec($_, 1, 2) = 1 == 4 00100000000000000000000000000000
- vec($_, 2, 2) = 1 == 16 00001000000000000000000000000000
- vec($_, 3, 2) = 1 == 64 00000010000000000000000000000000
- vec($_, 4, 2) = 1 == 256 00000000100000000000000000000000
- vec($_, 5, 2) = 1 == 1024 00000000001000000000000000000000
- vec($_, 6, 2) = 1 == 4096 00000000000010000000000000000000
- vec($_, 7, 2) = 1 == 16384 00000000000000100000000000000000
- vec($_, 8, 2) = 1 == 65536 00000000000000001000000000000000
- vec($_, 9, 2) = 1 == 262144 00000000000000000010000000000000
- vec($_,10, 2) = 1 == 1048576 00000000000000000000100000000000
- vec($_,11, 2) = 1 == 4194304 00000000000000000000001000000000
- vec($_,12, 2) = 1 == 16777216 00000000000000000000000010000000
- vec($_,13, 2) = 1 == 67108864 00000000000000000000000000100000
- vec($_,14, 2) = 1 == 268435456 00000000000000000000000000001000
- vec($_,15, 2) = 1 == 1073741824 00000000000000000000000000000010
- vec($_, 0, 2) = 2 == 2 01000000000000000000000000000000
- vec($_, 1, 2) = 2 == 8 00010000000000000000000000000000
- vec($_, 2, 2) = 2 == 32 00000100000000000000000000000000
- vec($_, 3, 2) = 2 == 128 00000001000000000000000000000000
- vec($_, 4, 2) = 2 == 512 00000000010000000000000000000000
- vec($_, 5, 2) = 2 == 2048 00000000000100000000000000000000
- vec($_, 6, 2) = 2 == 8192 00000000000001000000000000000000
- vec($_, 7, 2) = 2 == 32768 00000000000000010000000000000000
- vec($_, 8, 2) = 2 == 131072 00000000000000000100000000000000
- vec($_, 9, 2) = 2 == 524288 00000000000000000001000000000000
- vec($_,10, 2) = 2 == 2097152 00000000000000000000010000000000
- vec($_,11, 2) = 2 == 8388608 00000000000000000000000100000000
- vec($_,12, 2) = 2 == 33554432 00000000000000000000000001000000
- vec($_,13, 2) = 2 == 134217728 00000000000000000000000000010000
- vec($_,14, 2) = 2 == 536870912 00000000000000000000000000000100
- vec($_,15, 2) = 2 == 2147483648 00000000000000000000000000000001
- vec($_, 0, 4) = 1 == 1 10000000000000000000000000000000
- vec($_, 1, 4) = 1 == 16 00001000000000000000000000000000
- vec($_, 2, 4) = 1 == 256 00000000100000000000000000000000
- vec($_, 3, 4) = 1 == 4096 00000000000010000000000000000000
- vec($_, 4, 4) = 1 == 65536 00000000000000001000000000000000
- vec($_, 5, 4) = 1 == 1048576 00000000000000000000100000000000
- vec($_, 6, 4) = 1 == 16777216 00000000000000000000000010000000
- vec($_, 7, 4) = 1 == 268435456 00000000000000000000000000001000
- vec($_, 0, 4) = 2 == 2 01000000000000000000000000000000
- vec($_, 1, 4) = 2 == 32 00000100000000000000000000000000
- vec($_, 2, 4) = 2 == 512 00000000010000000000000000000000
- vec($_, 3, 4) = 2 == 8192 00000000000001000000000000000000
- vec($_, 4, 4) = 2 == 131072 00000000000000000100000000000000
- vec($_, 5, 4) = 2 == 2097152 00000000000000000000010000000000
- vec($_, 6, 4) = 2 == 33554432 00000000000000000000000001000000
- vec($_, 7, 4) = 2 == 536870912 00000000000000000000000000000100
- vec($_, 0, 4) = 4 == 4 00100000000000000000000000000000
- vec($_, 1, 4) = 4 == 64 00000010000000000000000000000000
- vec($_, 2, 4) = 4 == 1024 00000000001000000000000000000000
- vec($_, 3, 4) = 4 == 16384 00000000000000100000000000000000
- vec($_, 4, 4) = 4 == 262144 00000000000000000010000000000000
- vec($_, 5, 4) = 4 == 4194304 00000000000000000000001000000000
- vec($_, 6, 4) = 4 == 67108864 00000000000000000000000000100000
- vec($_, 7, 4) = 4 == 1073741824 00000000000000000000000000000010
- vec($_, 0, 4) = 8 == 8 00010000000000000000000000000000
- vec($_, 1, 4) = 8 == 128 00000001000000000000000000000000
- vec($_, 2, 4) = 8 == 2048 00000000000100000000000000000000
- vec($_, 3, 4) = 8 == 32768 00000000000000010000000000000000
- vec($_, 4, 4) = 8 == 524288 00000000000000000001000000000000
- vec($_, 5, 4) = 8 == 8388608 00000000000000000000000100000000
- vec($_, 6, 4) = 8 == 134217728 00000000000000000000000000010000
- vec($_, 7, 4) = 8 == 2147483648 00000000000000000000000000000001
- vec($_, 0, 8) = 1 == 1 10000000000000000000000000000000
- vec($_, 1, 8) = 1 == 256 00000000100000000000000000000000
- vec($_, 2, 8) = 1 == 65536 00000000000000001000000000000000
- vec($_, 3, 8) = 1 == 16777216 00000000000000000000000010000000
- vec($_, 0, 8) = 2 == 2 01000000000000000000000000000000
- vec($_, 1, 8) = 2 == 512 00000000010000000000000000000000
- vec($_, 2, 8) = 2 == 131072 00000000000000000100000000000000
- vec($_, 3, 8) = 2 == 33554432 00000000000000000000000001000000
- vec($_, 0, 8) = 4 == 4 00100000000000000000000000000000
- vec($_, 1, 8) = 4 == 1024 00000000001000000000000000000000
- vec($_, 2, 8) = 4 == 262144 00000000000000000010000000000000
- vec($_, 3, 8) = 4 == 67108864 00000000000000000000000000100000
- vec($_, 0, 8) = 8 == 8 00010000000000000000000000000000
- vec($_, 1, 8) = 8 == 2048 00000000000100000000000000000000
- vec($_, 2, 8) = 8 == 524288 00000000000000000001000000000000
- vec($_, 3, 8) = 8 == 134217728 00000000000000000000000000010000
- vec($_, 0, 8) = 16 == 16 00001000000000000000000000000000
- vec($_, 1, 8) = 16 == 4096 00000000000010000000000000000000
- vec($_, 2, 8) = 16 == 1048576 00000000000000000000100000000000
- vec($_, 3, 8) = 16 == 268435456 00000000000000000000000000001000
- vec($_, 0, 8) = 32 == 32 00000100000000000000000000000000
- vec($_, 1, 8) = 32 == 8192 00000000000001000000000000000000
- vec($_, 2, 8) = 32 == 2097152 00000000000000000000010000000000
- vec($_, 3, 8) = 32 == 536870912 00000000000000000000000000000100
- vec($_, 0, 8) = 64 == 64 00000010000000000000000000000000
- vec($_, 1, 8) = 64 == 16384 00000000000000100000000000000000
- vec($_, 2, 8) = 64 == 4194304 00000000000000000000001000000000
- vec($_, 3, 8) = 64 == 1073741824 00000000000000000000000000000010
- vec($_, 0, 8) = 128 == 128 00000001000000000000000000000000
- vec($_, 1, 8) = 128 == 32768 00000000000000010000000000000000
- vec($_, 2, 8) = 128 == 8388608 00000000000000000000000100000000
- vec($_, 3, 8) = 128 == 2147483648 00000000000000000000000000000001
+ 0 1 2 3
+ unpack("V",$_) 01234567890123456789012345678901
+ ------------------------------------------------------------------
+ vec($_, 0, 1) = 1 == 1 10000000000000000000000000000000
+ vec($_, 1, 1) = 1 == 2 01000000000000000000000000000000
+ vec($_, 2, 1) = 1 == 4 00100000000000000000000000000000
+ vec($_, 3, 1) = 1 == 8 00010000000000000000000000000000
+ vec($_, 4, 1) = 1 == 16 00001000000000000000000000000000
+ vec($_, 5, 1) = 1 == 32 00000100000000000000000000000000
+ vec($_, 6, 1) = 1 == 64 00000010000000000000000000000000
+ vec($_, 7, 1) = 1 == 128 00000001000000000000000000000000
+ vec($_, 8, 1) = 1 == 256 00000000100000000000000000000000
+ vec($_, 9, 1) = 1 == 512 00000000010000000000000000000000
+ vec($_,10, 1) = 1 == 1024 00000000001000000000000000000000
+ vec($_,11, 1) = 1 == 2048 00000000000100000000000000000000
+ vec($_,12, 1) = 1 == 4096 00000000000010000000000000000000
+ vec($_,13, 1) = 1 == 8192 00000000000001000000000000000000
+ vec($_,14, 1) = 1 == 16384 00000000000000100000000000000000
+ vec($_,15, 1) = 1 == 32768 00000000000000010000000000000000
+ vec($_,16, 1) = 1 == 65536 00000000000000001000000000000000
+ vec($_,17, 1) = 1 == 131072 00000000000000000100000000000000
+ vec($_,18, 1) = 1 == 262144 00000000000000000010000000000000
+ vec($_,19, 1) = 1 == 524288 00000000000000000001000000000000
+ vec($_,20, 1) = 1 == 1048576 00000000000000000000100000000000
+ vec($_,21, 1) = 1 == 2097152 00000000000000000000010000000000
+ vec($_,22, 1) = 1 == 4194304 00000000000000000000001000000000
+ vec($_,23, 1) = 1 == 8388608 00000000000000000000000100000000
+ vec($_,24, 1) = 1 == 16777216 00000000000000000000000010000000
+ vec($_,25, 1) = 1 == 33554432 00000000000000000000000001000000
+ vec($_,26, 1) = 1 == 67108864 00000000000000000000000000100000
+ vec($_,27, 1) = 1 == 134217728 00000000000000000000000000010000
+ vec($_,28, 1) = 1 == 268435456 00000000000000000000000000001000
+ vec($_,29, 1) = 1 == 536870912 00000000000000000000000000000100
+ vec($_,30, 1) = 1 == 1073741824 00000000000000000000000000000010
+ vec($_,31, 1) = 1 == 2147483648 00000000000000000000000000000001
+ vec($_, 0, 2) = 1 == 1 10000000000000000000000000000000
+ vec($_, 1, 2) = 1 == 4 00100000000000000000000000000000
+ vec($_, 2, 2) = 1 == 16 00001000000000000000000000000000
+ vec($_, 3, 2) = 1 == 64 00000010000000000000000000000000
+ vec($_, 4, 2) = 1 == 256 00000000100000000000000000000000
+ vec($_, 5, 2) = 1 == 1024 00000000001000000000000000000000
+ vec($_, 6, 2) = 1 == 4096 00000000000010000000000000000000
+ vec($_, 7, 2) = 1 == 16384 00000000000000100000000000000000
+ vec($_, 8, 2) = 1 == 65536 00000000000000001000000000000000
+ vec($_, 9, 2) = 1 == 262144 00000000000000000010000000000000
+ vec($_,10, 2) = 1 == 1048576 00000000000000000000100000000000
+ vec($_,11, 2) = 1 == 4194304 00000000000000000000001000000000
+ vec($_,12, 2) = 1 == 16777216 00000000000000000000000010000000
+ vec($_,13, 2) = 1 == 67108864 00000000000000000000000000100000
+ vec($_,14, 2) = 1 == 268435456 00000000000000000000000000001000
+ vec($_,15, 2) = 1 == 1073741824 00000000000000000000000000000010
+ vec($_, 0, 2) = 2 == 2 01000000000000000000000000000000
+ vec($_, 1, 2) = 2 == 8 00010000000000000000000000000000
+ vec($_, 2, 2) = 2 == 32 00000100000000000000000000000000
+ vec($_, 3, 2) = 2 == 128 00000001000000000000000000000000
+ vec($_, 4, 2) = 2 == 512 00000000010000000000000000000000
+ vec($_, 5, 2) = 2 == 2048 00000000000100000000000000000000
+ vec($_, 6, 2) = 2 == 8192 00000000000001000000000000000000
+ vec($_, 7, 2) = 2 == 32768 00000000000000010000000000000000
+ vec($_, 8, 2) = 2 == 131072 00000000000000000100000000000000
+ vec($_, 9, 2) = 2 == 524288 00000000000000000001000000000000
+ vec($_,10, 2) = 2 == 2097152 00000000000000000000010000000000
+ vec($_,11, 2) = 2 == 8388608 00000000000000000000000100000000
+ vec($_,12, 2) = 2 == 33554432 00000000000000000000000001000000
+ vec($_,13, 2) = 2 == 134217728 00000000000000000000000000010000
+ vec($_,14, 2) = 2 == 536870912 00000000000000000000000000000100
+ vec($_,15, 2) = 2 == 2147483648 00000000000000000000000000000001
+ vec($_, 0, 4) = 1 == 1 10000000000000000000000000000000
+ vec($_, 1, 4) = 1 == 16 00001000000000000000000000000000
+ vec($_, 2, 4) = 1 == 256 00000000100000000000000000000000
+ vec($_, 3, 4) = 1 == 4096 00000000000010000000000000000000
+ vec($_, 4, 4) = 1 == 65536 00000000000000001000000000000000
+ vec($_, 5, 4) = 1 == 1048576 00000000000000000000100000000000
+ vec($_, 6, 4) = 1 == 16777216 00000000000000000000000010000000
+ vec($_, 7, 4) = 1 == 268435456 00000000000000000000000000001000
+ vec($_, 0, 4) = 2 == 2 01000000000000000000000000000000
+ vec($_, 1, 4) = 2 == 32 00000100000000000000000000000000
+ vec($_, 2, 4) = 2 == 512 00000000010000000000000000000000
+ vec($_, 3, 4) = 2 == 8192 00000000000001000000000000000000
+ vec($_, 4, 4) = 2 == 131072 00000000000000000100000000000000
+ vec($_, 5, 4) = 2 == 2097152 00000000000000000000010000000000
+ vec($_, 6, 4) = 2 == 33554432 00000000000000000000000001000000
+ vec($_, 7, 4) = 2 == 536870912 00000000000000000000000000000100
+ vec($_, 0, 4) = 4 == 4 00100000000000000000000000000000
+ vec($_, 1, 4) = 4 == 64 00000010000000000000000000000000
+ vec($_, 2, 4) = 4 == 1024 00000000001000000000000000000000
+ vec($_, 3, 4) = 4 == 16384 00000000000000100000000000000000
+ vec($_, 4, 4) = 4 == 262144 00000000000000000010000000000000
+ vec($_, 5, 4) = 4 == 4194304 00000000000000000000001000000000
+ vec($_, 6, 4) = 4 == 67108864 00000000000000000000000000100000
+ vec($_, 7, 4) = 4 == 1073741824 00000000000000000000000000000010
+ vec($_, 0, 4) = 8 == 8 00010000000000000000000000000000
+ vec($_, 1, 4) = 8 == 128 00000001000000000000000000000000
+ vec($_, 2, 4) = 8 == 2048 00000000000100000000000000000000
+ vec($_, 3, 4) = 8 == 32768 00000000000000010000000000000000
+ vec($_, 4, 4) = 8 == 524288 00000000000000000001000000000000
+ vec($_, 5, 4) = 8 == 8388608 00000000000000000000000100000000
+ vec($_, 6, 4) = 8 == 134217728 00000000000000000000000000010000
+ vec($_, 7, 4) = 8 == 2147483648 00000000000000000000000000000001
+ vec($_, 0, 8) = 1 == 1 10000000000000000000000000000000
+ vec($_, 1, 8) = 1 == 256 00000000100000000000000000000000
+ vec($_, 2, 8) = 1 == 65536 00000000000000001000000000000000
+ vec($_, 3, 8) = 1 == 16777216 00000000000000000000000010000000
+ vec($_, 0, 8) = 2 == 2 01000000000000000000000000000000
+ vec($_, 1, 8) = 2 == 512 00000000010000000000000000000000
+ vec($_, 2, 8) = 2 == 131072 00000000000000000100000000000000
+ vec($_, 3, 8) = 2 == 33554432 00000000000000000000000001000000
+ vec($_, 0, 8) = 4 == 4 00100000000000000000000000000000
+ vec($_, 1, 8) = 4 == 1024 00000000001000000000000000000000
+ vec($_, 2, 8) = 4 == 262144 00000000000000000010000000000000
+ vec($_, 3, 8) = 4 == 67108864 00000000000000000000000000100000
+ vec($_, 0, 8) = 8 == 8 00010000000000000000000000000000
+ vec($_, 1, 8) = 8 == 2048 00000000000100000000000000000000
+ vec($_, 2, 8) = 8 == 524288 00000000000000000001000000000000
+ vec($_, 3, 8) = 8 == 134217728 00000000000000000000000000010000
+ vec($_, 0, 8) = 16 == 16 00001000000000000000000000000000
+ vec($_, 1, 8) = 16 == 4096 00000000000010000000000000000000
+ vec($_, 2, 8) = 16 == 1048576 00000000000000000000100000000000
+ vec($_, 3, 8) = 16 == 268435456 00000000000000000000000000001000
+ vec($_, 0, 8) = 32 == 32 00000100000000000000000000000000
+ vec($_, 1, 8) = 32 == 8192 00000000000001000000000000000000
+ vec($_, 2, 8) = 32 == 2097152 00000000000000000000010000000000
+ vec($_, 3, 8) = 32 == 536870912 00000000000000000000000000000100
+ vec($_, 0, 8) = 64 == 64 00000010000000000000000000000000
+ vec($_, 1, 8) = 64 == 16384 00000000000000100000000000000000
+ vec($_, 2, 8) = 64 == 4194304 00000000000000000000001000000000
+ vec($_, 3, 8) = 64 == 1073741824 00000000000000000000000000000010
+ vec($_, 0, 8) = 128 == 128 00000001000000000000000000000000
+ vec($_, 1, 8) = 128 == 32768 00000000000000010000000000000000
+ vec($_, 2, 8) = 128 == 8388608 00000000000000000000000100000000
+ vec($_, 3, 8) = 128 == 2147483648 00000000000000000000000000000001
=item wait
X<wait>
+=for Pod::Functions wait for any child process to die
+
Behaves like wait(2) on your system: it waits for a child
process to terminate and returns the pid of the deceased process, or
C<-1> if there are no child processes. The status is returned in C<$?>
=item waitpid PID,FLAGS
X<waitpid>
+=for Pod::Functions wait for a particular child process to die
+
Waits for a particular child process to terminate and returns the pid of
the deceased process, or C<-1> if there is no such child process. On some
systems, a value of 0 indicates that there are processes still running.
=item wantarray
X<wantarray> X<context>
+=for Pod::Functions get void vs scalar vs list context of current subroutine call
+
Returns true if the context of the currently executing subroutine or
C<eval> is looking for a list value. Returns false if the context is
looking for a scalar. Returns the undefined value if the context is
=item warn LIST
X<warn> X<warning> X<STDERR>
+=for Pod::Functions print debugging info
+
Prints the value of LIST to STDERR. If the last element of LIST does
not end in a newline, it appends the same file/line number text as C<die>
does.
examples. See the Carp module for other kinds of warnings using its
carp() and cluck() functions.
-=item when EXPR BLOCK
-X<when>
-
-=item when BLOCK
-
-C<when> is analogous to the C<case>
-keyword in other languages. Used with a
-C<foreach> loop or the experimental C<given> block, C<when> can be used in
-Perl to implement C<switch>/C<case> like statements. Available as a
-statement after Perl 5.10 and as a statement modifier after 5.14.
-Here are three examples:
-
- use v5.10;
- foreach (@fruits) {
- when (/apples?/) {
- say "I like apples."
- }
- when (/oranges?/) {
- say "I don't like oranges."
- }
- default {
- say "I don't like anything"
- }
- }
-
- # require 5.14 for when as statement modifier
- use v5.14;
- foreach (@fruits) {
- say "I like apples." when /apples?/;
- say "I don't like oranges." when /oranges?;
- default { say "I don't like anything" }
- }
-
- use v5.10;
- given ($fruit) {
- when (/apples?/) {
- say "I like apples."
- }
- when (/oranges?/) {
- say "I don't like oranges."
- }
- default {
- say "I don't like anything"
- }
- }
-
-See L<perlsyn/"Switch Statements"> for detailed information.
-
=item write FILEHANDLE
X<write>
=item write
+=for Pod::Functions print a picture record
+
Writes a formatted record (possibly multi-line) to the specified FILEHANDLE,
using the format associated with that file. By default the format for
a file is the one having the same name as the filehandle, but the
=item y///
+=for Pod::Functions transliterate a string
+
The transliteration operator. Same as C<tr///>. See
L<perlop/"Quote and Quote-like Operators">.
=item __END__
-These keywords are documented in L<perldata>.
+These keywords are documented in L<perldata/"Special Literals">.
=back
=item CHECK
-=item DESTROY
-
=item END
=item INIT
=item UNITCHECK
-These keywords are documented in L<perlmod>.
+These compile phase keywords are documented in L<perlmod/"BEGIN, UNITCHECK, CHECK, INIT and END">.
+
+=back
+
+=head3 perlobj
+
+=over
+
+=item DESTROY
+
+This method keyword is documented in L<perlobj/"Destructors">.
=back
=item AUTOLOAD
-These are documented in L<perlsub>.
+This keyword is documented in L<perlsub/"Autoloading">.
=back
-=head2 perlsyn
+=head3 perlsyn
=over
=item while
-These flow-control keywords are documented in L<perlsyn>.
+These flow-control keywords are documented in L<perlsyn/"Compound Statements">.
+
+=back
+
+=over
+
+=item default
+
+=item given
+
+=item when
+
+These flow-control keywords related to the experimental switch feature are
+documented in L<perlsyn/"Switch Statements"> .
=back
https://perl5.git.perl.org / perl5.git / blobdiff