($package, $filename, $line, $subroutine, $hasargs,
$wantarray, $evaltext, $is_require, $hints) = caller($i);
-Here $subroutine may be C<"(eval)"> if the frame is not a subroutine
+Here $subroutine may be C<(eval)> if the frame is not a subroutine
call, but an C<eval>. In such a case additional elements $evaltext and
C<$is_require> are set: C<$is_require> is true if the frame is created by a
C<require> or C<use> statement, $evaltext contains the text of the
C<eval EXPR> statement. In particular, for a C<eval BLOCK> statement,
-$filename is C<"(eval)">, but $evaltext is undefined. (Note also that
+$filename is C<(eval)>, but $evaltext is undefined. (Note also that
each C<use> statement creates a C<require> frame inside an C<eval EXPR>)
frame. C<$hints> contains pragmatic hints that the caller was
-compiled with. It currently only reflects the hint corresponding to
-C<use utf8>.
+compiled with. The C<$hints> value is subject to change between versions
+of Perl, and is not meant for external use.
Furthermore, when called from within the DB package, caller returns more
detailed information: it sets the list variable C<@DB::args> to be the
=item chdir EXPR
Changes the working directory to EXPR, if possible. If EXPR is omitted,
-changes to the user's home directory. Returns true upon success,
-false otherwise. See the example under C<die>.
+changes to the directory specified by C<$ENV{HOME}>, if set; if not,
+changes to the directory specified by C<$ENV{LOGDIR}>. If neither is
+set, C<chdir> does nothing. It returns true upon success, false
+otherwise. See the example under C<die>.
=item chmod LIST
This function works like the system call by the same name: it makes the
named directory the new root directory for all further pathnames that
-begin with a C<"/"> by your process and all its children. (It doesn't
+begin with a C</> by your process and all its children. (It doesn't
change your current working directory, which is unaffected.) For security
reasons, this call is restricted to the superuser. If FILENAME is
omitted, does a C<chroot> to C<$_>.
=item delete EXPR
-Deletes the specified key(s) and their associated values from a hash.
-For each key, returns the deleted value associated with that key, or
-the undefined value if there was no such key. Deleting from C<$ENV{}>
-modifies the environment. Deleting from a hash tied to a DBM file
-deletes the entry from the DBM file. (But deleting from a C<tie>d hash
-doesn't necessarily return anything.)
+Given an expression that specifies a hash element, array element, hash slice,
+or array slice, deletes the specified element(s) from the hash or array.
+If the array elements happen to be at the end of the array, the size
+of the array will shrink by that number of elements.
-The following deletes all the values of a hash:
+Returns each element so deleted or the undefined value if there was no such
+element. Deleting from C<$ENV{}> modifies the environment. Deleting from
+a hash tied to a DBM file deletes the entry from the DBM file. Deleting
+from a C<tie>d hash or array may not necessarily return anything.
+
+Deleting an array element effectively returns that position of the array
+to its initial, uninitialized state. Subsequently testing for the same
+element with exists() will return false. See L</exists>.
+
+The following (inefficiently) deletes all the values of %HASH and @ARRAY:
foreach $key (keys %HASH) {
delete $HASH{$key};
}
-And so does this:
+ foreach $index (0 .. $#ARRAY) {
+ delete $ARRAY[$index];
+ }
+
+And so do these:
+
+ delete @HASH{keys %HASH};
- delete @HASH{keys %HASH}
+ delete @ARRAY[0 .. $#ARRAY];
But both of these are slower than just assigning the empty list
-or undefining it:
+or undefining %HASH or @ARRAY:
- %hash = (); # completely empty %hash
- undef %hash; # forget %hash every existed
+ %HASH = (); # completely empty %HASH
+ undef %HASH; # forget %HASH ever existed
+
+ @ARRAY = (); # completely empty @ARRAY
+ undef @ARRAY; # forget @ARRAY ever existed
Note that the EXPR can be arbitrarily complicated as long as the final
-operation is a hash element lookup or hash slice:
+operation is a hash element, array element, hash slice, or array slice
+lookup:
delete $ref->[$x][$y]{$key};
delete @{$ref->[$x][$y]}{$key1, $key2, @morekeys};
+ delete $ref->[$x][$y][$index];
+ delete @{$ref->[$x][$y]}[$index1, $index2, @moreindices];
+
=item die LIST
Outside an C<eval>, prints the value of LIST to C<STDERR> and
C<eof(FILEHANDLE)> on it) after end-of-file is reached. File types such
as terminals may lose the end-of-file condition if you do.
-An C<eof> without an argument uses the last file read as argument.
-Using C<eof()> with empty parentheses is very different. It indicates
-the pseudo file formed of the files listed on the command line,
-i.e., C<eof()> is reasonable to use inside a C<while (E<lt>E<gt>)>
-loop to detect the end of only the last file. Use C<eof(ARGV)> or
-C<eof> without the parentheses to test I<each> file in a while
-(E<lt>E<gt>) loop. Examples:
+An C<eof> without an argument uses the last file read. Using C<eof()>
+with empty parentheses is very different. It refers to the pseudo file
+formed from the files listed on the command line and accessed via the
+C<E<lt>E<gt>> operator. Since C<E<lt>E<gt>> isn't explicitly opened,
+as a normal filehandle is, an C<eof()> before C<E<lt>E<gt>> has been
+used will cause C<@ARGV> to be examined to determine if input is
+available.
+
+In a C<while (E<lt>E<gt>)> loop, C<eof> or C<eof(ARGV)> can be used to
+detect the end of each file, C<eof()> will only detect the end of the
+last file. Examples:
# reset line numbering on each input file
while (<>) {
}
Practical hint: you almost never need to use C<eof> in Perl, because the
-input operators return false values when they run out of data, or if there
-was an error.
+input operators typically return C<undef> when they run out of data, or if
+there was an error.
=item eval EXPR
=item exists EXPR
-Returns true if the specified hash key exists in its hash, even
-if the corresponding value is undefined.
+Given an expression that specifies a hash element or array element,
+returns true if the specified element in the hash or array has ever
+been initialized, even if the corresponding value is undefined. The
+element is not autovivified if it doesn't exist.
- print "Exists\n" if exists $array{$key};
- print "Defined\n" if defined $array{$key};
- print "True\n" if $array{$key};
+ print "Exists\n" if exists $hash{$key};
+ print "Defined\n" if defined $hash{$key};
+ print "True\n" if $hash{$key};
-A hash element can be true only if it's defined, and defined if
+ print "Exists\n" if exists $array[$index];
+ print "Defined\n" if defined $array[$index];
+ print "True\n" if $array[$index];
+
+A hash or array element can be true only if it's defined, and defined if
it exists, but the reverse doesn't necessarily hold true.
+Given an expression that specifies the name of a subroutine,
+returns true if the specified subroutine has ever been declared, even
+if it is undefined. Mentioning a subroutine name for exists or defined
+does not count as declaring it.
+
+ print "Exists\n" if exists &subroutine;
+ print "Defined\n" if defined &subroutine;
+
Note that the EXPR can be arbitrarily complicated as long as the final
-operation is a hash key lookup:
+operation is a hash or array key lookup or subroutine name:
if (exists $ref->{A}->{B}->{$key}) { }
if (exists $hash{A}{B}{$key}) { }
-Although the last element will not spring into existence just because
-its existence was tested, intervening ones will. Thus C<$ref-E<gt>{"A"}>
-and C<$ref-E<gt>{"A"}-E<gt>{"B"}> will spring into existence due to the
-existence test for a $key element. This happens anywhere the arrow
-operator is used, including even
+ if (exists $ref->{A}->{B}->[$ix]) { }
+ if (exists $hash{A}{B}[$ix]) { }
+
+ if (exists &{$ref->{A}{B}{$key}}) { }
+
+Although the deepest nested array or hash will not spring into existence
+just because its existence was tested, any intervening ones will.
+Thus C<$ref-E<gt>{"A"}> and C<$ref-E<gt>{"A"}-E<gt>{"B"}> will spring
+into existence due to the existence test for the $key element above.
+This happens anywhere the arrow operator is used, including even:
undef $ref;
if (exists $ref->{"Some key"}) { }
second--glance appear to be an lvalue context may be fixed in a future
release.
+See L<perlref/"Pseudo-hashes"> for specifics on how exists() acts when
+used on a pseudo-hash.
+
+Use of a subroutine call, rather than a subroutine name, as an argument
+to exists() is an error.
+
+ exists ⊂ # OK
+ exists &sub(); # Error
+
=item exit EXPR
Evaluates EXPR and exits immediately with that value. Example:
or die "can't fcntl F_GETFL: $!";
You don't have to check for C<defined> on the return from C<fnctl>.
-Like C<ioctl>, it maps a C<0> return from the system call into C<"0
-but true"> in Perl. This string is true in boolean context and C<0>
+Like C<ioctl>, it maps a C<0> return from the system call into
+C<"0 but true"> in Perl. This string is true in boolean context and C<0>
in numeric context. It is also exempt from the normal B<-w> warnings
on improper numeric conversions.
OPERATION is one of LOCK_SH, LOCK_EX, or LOCK_UN, possibly combined with
LOCK_NB. These constants are traditionally valued 1, 2, 8 and 4, but
-you can use the symbolic names if import them from the Fcntl module,
+you can use the symbolic names if you import them from the Fcntl module,
either individually, or as a group using the ':flock' tag. LOCK_SH
requests a shared lock, LOCK_EX requests an exclusive lock, and LOCK_UN
-releases a previously requested lock. If LOCK_NB is added to LOCK_SH or
-LOCK_EX then C<flock> will return immediately rather than blocking
+releases a previously requested lock. If LOCK_NB is bitwise-or'ed with
+LOCK_SH or LOCK_EX then C<flock> will return immediately rather than blocking
waiting for the lock (check the return status to see if you got it).
To avoid the possibility of miscoordination, Perl now flushes FILEHANDLE
then you create non-Y2K-compliant programs--and you wouldn't want to do
that, would you?
+The proper way to get a complete 4-digit year is simply:
+
+ $year += 1900;
+
+And to get the last two digits of the year (e.g., '01' in 2001) do:
+
+ $year = sprintf("%02d", $year % 100);
+
If EXPR is omitted, does C<gmtime(time())>.
In scalar context, returns the ctime(3) value:
goto ("FOO", "BAR", "GLARCH")[$i];
-The C<goto-&NAME> form is highly magical, and substitutes a call to the
-named subroutine for the currently running subroutine. This is used by
-C<AUTOLOAD> subroutines that wish to load another subroutine and then
-pretend that the other subroutine had been called in the first place
-(except that any modifications to C<@_> in the current subroutine are
-propagated to the other subroutine.) After the C<goto>, not even C<caller>
-will be able to tell that this routine was called first.
+The C<goto-&NAME> form is quite different from the other forms of C<goto>.
+In fact, it isn't a goto in the normal sense at all, and doesn't have
+the stigma associated with other gotos. Instead, it
+substitutes a call to the named subroutine for the currently running
+subroutine. This is used by C<AUTOLOAD> subroutines that wish to load
+another subroutine and then pretend that the other subroutine had been
+called in the first place (except that any modifications to C<@_>
+in the current subroutine are propagated to the other subroutine.)
+After the C<goto>, not even C<caller> will be able to tell that this
+routine was called first.
+
+NAME needn't be the name of a subroutine; it can be a scalar variable
+containing a code reference, or a block which evaluates to a code
+reference.
=item grep BLOCK LIST
print hex 'aF'; # same
Hex strings may only represent integers. Strings that would cause
-integer overflow trigger a mandatory error message.
+integer overflow trigger a warning.
=item import
See also C<each>, C<values> and C<sort>.
-=item kill LIST
+=item kill SIGNAL, LIST
-Sends a signal to a list of processes. The first element of
-the list must be the signal to send. Returns the number of
+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).
$cnt = kill 1, $child1, $child2;
kill 9, @goners;
-Unlike in the shell, in Perl if the I<SIGNAL> is negative, it kills
+If SIGNAL is zero, no signal is sent to the process. This is a
+useful way to check that the process is alive and hasn't changed
+its UID. See L<perlport> for notes on the portability of this
+construct.
+
+Unlike in the shell, if SIGNAL is negative, it kills
process groups instead of processes. (On System V, a negative I<PROCESS>
number will also kill process groups, but that's not portable.) That
means you usually want to use positive not negative signals. You may also
C<eval {}>, C<sub {}> or C<do {}>, and should not be used to exit
a grep() or map() operation.
+Note that a block by itself is semantically identical to a loop
+that executes once. Thus C<last> can be used to effect an early
+exit out of such a block.
+
See also L</continue> for an illustration of how C<last>, C<next>, and
C<redo> work.
then you create non-Y2K-compliant programs--and you wouldn't want to do
that, would you?
+The proper way to get a complete 4-digit year is simply:
+
+ $year += 1900;
+
+And to get the last two digits of the year (e.g., '01' in 2001) do:
+
+ $year = sprintf("%02d", $year % 100);
+
If EXPR is omitted, uses the current time (C<localtime(time)>).
In scalar context, returns the ctime(3) value:
first to get the correct constant definitions. If CMD is C<IPC_STAT>,
then ARG must be a variable which will hold the returned C<msqid_ds>
-structure. Returns like C<ioctl>: the undefined value for error, C<"0 but
-true"> for zero, or the actual return value otherwise. See also
+structure. Returns like C<ioctl>: the undefined value for error,
+C<"0 but true"> for zero, or the actual return value otherwise. See also
C<IPC::SysV> and C<IPC::Semaphore> documentation.
=item msgget KEY,FLAGS
C<eval {}>, C<sub {}> or C<do {}>, and should not be used to exit
a grep() or map() operation.
+Note that a block by itself is semantically identical to a loop
+that executes once. Thus C<next> will exit such a block early.
+
See also L</continue> for an illustration of how C<last>, C<next>, and
C<redo> work.
open(FILEHANDLE, "<&=$fd")
+Note that this feature depends on the fdopen() C library function.
+On many UNIX systems, fdopen() is known to fail when file descriptors
+exceed a certain value, typically 255. If you need more file
+descriptors than that, consider rebuilding Perl to use the C<sfio>
+library.
+
If you open a pipe on the command C<'-'>, i.e., either C<'|-'> or C<'-|'>
with 2-arguments (or 1-argument) form of open(), then
there is an implicit fork done, and the return value of open is the pid
EXPR is omitted, uses C<$_>. For the reverse, see L</chr>.
See L<utf8> for more about Unicode.
+=item our EXPR
+
+An C<our> declares the listed variables to be valid globals within
+the enclosing block, file, or C<eval>. That is, it has the same
+scoping rules as a "my" declaration, but does not create a local
+variable. If more than one value is listed, the list must be placed
+in parentheses. The C<our> declaration has no semantic effect unless
+"use strict vars" is in effect, in which case it lets you use the
+declared global variable without qualifying it with a package name.
+(But only within the lexical scope of the C<our> declaration. In this
+it differs from "use vars", which is package scoped.)
+
+An C<our> declaration declares a global 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
+behavior holds:
+
+ package Foo;
+ our $bar; # declares $Foo::bar for rest of lexical scope
+ $bar = 20;
+
+ package Bar;
+ print $bar; # prints 20
+
+Multiple C<our> declarations in the same lexical scope are allowed
+if they are in different packages. If they happened to be in the same
+package, Perl will emit warnings if you have asked for them.
+
+ use warnings;
+ package Foo;
+ our $bar; # declares $Foo::bar for rest of lexical scope
+ $bar = 20;
+
+ package Bar;
+ our $bar = 30; # declares $Bar::bar for rest of lexical scope
+ print $bar; # prints 30
+
+ our $bar; # emits warning
+
=item pack TEMPLATE,LIST
-Takes a list of values and packs it into a binary structure,
-returning the string containing the structure. The TEMPLATE is a
+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
+like its machine-level representation. For example, on 32-bit machines
+a converted integer may be represented by a sequence of 4 bytes.
+
+The TEMPLATE is a
sequence of characters that give the order and type of values, as
follows:
A An ascii string, will be space padded.
Z A null terminated (asciz) string, will be null padded.
- b A bit string (ascending bit order, like vec()).
- B A bit string (descending bit order).
+ b A bit string (ascending bit order inside each byte, like vec()).
+ B A bit string (descending bit order inside each byte).
h A hex string (low nybble first).
H A hex string (high nybble first).
what a local C compiler calls 'long'. If you want
native-length longs, use the '!' suffix.)
- n A short in "network" (big-endian) order.
- N A long in "network" (big-endian) order.
- v A short in "VAX" (little-endian) order.
- V A long in "VAX" (little-endian) order.
+ n An unsigned short in "network" (big-endian) order.
+ N An unsigned long in "network" (big-endian) order.
+ v An unsigned short in "VAX" (little-endian) order.
+ V An unsigned long in "VAX" (little-endian) order.
(These 'shorts' and 'longs' are _exactly_ 16 bits and
_exactly_ 32 bits, respectively.)
=item *
Each letter may optionally be followed by a number giving a repeat
-count. With all types except C<"a">, C<"A">, C<"Z">, C<"b">, C<"B">, C<"h">,
-C<"H">, and C<"P"> the pack function will gobble up that many values from
+count. With all types except C<a>, C<A>, C<Z>, C<b>, C<B>, C<h>,
+C<H>, and C<P> the pack function will gobble up that many values from
the LIST. A C<*> for the repeat count means to use however many items are
-left.
+left, except for C<@>, C<x>, C<X>, where it is equivalent
+to C<0>, and C<u>, where it is equivalent to 1 (or 45, what is the
+same).
+
+When used with C<Z>, C<*> results in the addition of a trailing null
+byte (so the packed result will be one longer than the byte C<length>
+of the item).
+
+The repeat count for C<u> is interpreted as the maximal number of bytes
+to encode per line of output, with 0 and 1 replaced by 45.
=item *
-The C<"a">, C<"A">, and C<"Z"> types gobble just one value, but pack it as a
+The C<a>, C<A>, and C<Z> types gobble just one value, but pack it as a
string of length count, padding with nulls or spaces as necessary. When
-unpacking, C<"A"> strips trailing spaces and nulls, C<"Z"> strips everything
-after the first null, and C<"a"> returns data verbatim.
+unpacking, C<A> strips trailing spaces and nulls, C<Z> strips everything
+after the first null, and C<a> returns data verbatim. When packing,
+C<a>, and C<Z> are equivalent.
+
+If the value-to-pack is too long, it is truncated. If too long and an
+explicit count is provided, C<Z> packs only C<$count-1> bytes, followed
+by a null byte. Thus C<Z> always packs a trailing null byte under
+all circumstances.
=item *
-Likewise, the C<"b"> and C<"B"> fields pack a string that many bits long.
+Likewise, the C<b> and C<B> fields pack a string that many bits long.
+Each byte of the input field of pack() generates 1 bit of the result.
+Each result bit is based on the least-significant bit of the corresponding
+input byte, i.e., on C<ord($byte)%2>. In particular, bytes C<"0"> and
+C<"1"> generate bits 0 and 1, as do bytes C<"\0"> and C<"\1">.
+
+Starting from the beginning of the input string of pack(), each 8-tuple
+of bytes is converted to 1 byte of output. With format C<b>
+the first byte of the 8-tuple determines the least-significant bit of a
+byte, and with format C<B> it determines the most-significant bit of
+a byte.
+
+If the length of the input string is not exactly divisible by 8, the
+remainder is packed as if the input string were padded by null bytes
+at the end. Similarly, during unpack()ing the "extra" bits are ignored.
+
+If the input string of pack() is longer than needed, extra bytes are ignored.
+A C<*> for the repeat count of pack() means to use all the bytes of
+the input field. On unpack()ing the bits are converted to a string
+of C<"0">s and C<"1">s.
=item *
-The C<"h"> and C<"H"> fields pack a string that many nybbles (4-bit groups,
+The C<h> and C<H> fields pack a string that many nybbles (4-bit groups,
representable as hexadecimal digits, 0-9a-f) long.
+Each byte of the input field of pack() generates 4 bits of the result.
+For non-alphabetical bytes the result is based on the 4 least-significant
+bits of the input byte, i.e., on C<ord($byte)%16>. In particular,
+bytes C<"0"> and C<"1"> generate nybbles 0 and 1, as do bytes
+C<"\0"> and C<"\1">. For bytes C<"a".."f"> and C<"A".."F"> the result
+is compatible with the usual hexadecimal digits, so that C<"a"> and
+C<"A"> both generate the nybble C<0xa==10>. The result for bytes
+C<"g".."z"> and C<"G".."Z"> is not well-defined.
+
+Starting from the beginning of the input string of pack(), each pair
+of bytes is converted to 1 byte of output. With format C<h> the
+first byte of the pair determines the least-significant nybble of the
+output byte, and with format C<H> it determines the most-significant
+nybble.
+
+If the length of the input string is not even, it behaves as if padded
+by a null byte at the end. Similarly, during unpack()ing the "extra"
+nybbles are ignored.
+
+If the input string of pack() is longer than needed, extra bytes are ignored.
+A C<*> for the repeat count of pack() means to use all the bytes of
+the input field. On unpack()ing the bits are converted to a string
+of hexadecimal digits.
+
=item *
-The C<"p"> type packs a pointer to a null-terminated string. You are
+The C<p> type packs a pointer to a null-terminated string. You are
responsible for ensuring the string is not a temporary value (which can
potentially get deallocated before you get around to using the packed result).
-The C<"P"> type packs a pointer to a structure of the size indicated by the
-length. A NULL pointer is created if the corresponding value for C<"p"> or
-C<"P"> is C<undef>.
+The C<P> type packs a pointer to a structure of the size indicated by the
+length. A NULL pointer is created if the corresponding value for C<p> or
+C<P> is C<undef>, similarly for unpack().
=item *
-The C<"#"> character allows packing and unpacking of strings where the
-packed structure contains a byte count followed by the string itself.
-You write I<length-item>C<#>I<string-item>.
+The C</> template character allows packing and unpacking of strings where
+the packed structure contains a byte count followed by the string itself.
+You write I<length-item>C</>I<string-item>.
The I<length-item> can be any C<pack> template letter,
and describes how the length value is packed.
The ones likely to be of most use are integer-packing ones like
-C<"n"> (for Java strings), C<"w"> (for ASN.1 or SNMP)
-and C<"N"> (for Sun XDR).
+C<n> (for Java strings), C<w> (for ASN.1 or SNMP)
+and C<N> (for Sun XDR).
The I<string-item> must, at present, be C<"A*">, C<"a*"> or C<"Z*">.
For C<unpack> the length of the string is obtained from the I<length-item>,
but if you put in the '*' it will be ignored.
- unpack 'C#a', "\04Gurusamy"; gives 'Guru'
- unpack 'a3#A* A*', '007 Bond J '; gives (' Bond','J')
- pack 'n#a* w#a*','hello,','world'; gives "\000\006hello,\005world"
+ unpack 'C/a', "\04Gurusamy"; gives 'Guru'
+ unpack 'a3/A* A*', '007 Bond J '; gives (' Bond','J')
+ pack 'n/a* w/a*','hello,','world'; gives "\000\006hello,\005world"
The I<length-item> is not returned explicitly from C<unpack>.
-Adding a count to the I<length-item> letter
-is unlikely to do anything useful,
-unless that letter is C<"A">, C<"a"> or C<"Z">.
-Packing with a I<length-item> of C<"a"> or C<"Z">
-may introduce C<"\000"> characters,
+Adding a count to the I<length-item> letter is unlikely to do anything
+useful, unless that letter is C<A>, C<a> or C<Z>. Packing with a
+I<length-item> of C<a> or C<Z> may introduce C<"\000"> characters,
which Perl does not regard as legal in numeric strings.
=item *
-The integer types C<"s">, C<"S">, C<"l">, and C<"L"> may be
-immediately followed by a C<"!"> suffix to signify native shorts or
-longs--as you can see from above for example a bare C<"l"> does mean
+The integer types C<s>, C<S>, C<l>, and C<L> may be
+immediately followed by a C<!> suffix to signify native shorts or
+longs--as you can see from above for example a bare C<l> does mean
exactly 32 bits, the native C<long> (as seen by the local C compiler)
may be larger. This is an issue mainly in 64-bit platforms. You can
-see whether using C<"!"> makes any difference by
+see whether using C<!> makes any difference by
print length(pack("s")), " ", length(pack("s!")), "\n";
print length(pack("l")), " ", length(pack("l!")), "\n";
-C<"i!"> and C<"I!"> also work but only because of completeness;
-they are identical to C<"i"> and C<"I">.
+C<i!> and C<I!> also work but only because of completeness;
+they are identical to C<i> and C<I>.
The actual sizes (in bytes) of native shorts, ints, longs, and long
longs on the platform where Perl was built are also available via
print $Config{longsize}, "\n";
print $Config{longlongsize}, "\n";
-(The C<$Config{longlongsize}> will be empty if your system does
+(The C<$Config{longlongsize}> will be undefine if your system does
not support long longs.)
=item *
-The integer formats C<"s">, C<"S">, C<"i">, C<"I">, C<"l">, and C<"L">
+The integer formats C<s>, C<S>, C<i>, C<I>, C<l>, and C<L>
are inherently non-portable between processors and operating systems
because they obey the native byteorder and endianness. For example a
-4-byte integer 0x87654321 (2271560481 decimal) be ordered natively
+4-byte integer 0x12345678 (305419896 decimal) be ordered natively
(arranged in and handled by the CPU registers) into bytes as
0x12 0x34 0x56 0x78 # little-endian
0x78 0x56 0x34 0x12 # big-endian
-Basically, the Intel, Alpha, and VAX CPUs and little-endian, while
+Basically, the Intel, Alpha, and VAX CPUs are little-endian, while
everybody else, for example Motorola m68k/88k, PPC, Sparc, HP PA,
Power, and Cray are big-endian. MIPS can be either: Digital used it
in little-endian mode; SGI uses it in big-endian mode.
Plea for Peace" by Danny Cohen, USC/ISI IEN 137, April 1, 1980) and
the egg-eating habits of the Lilliputians.
-Some systems may even have weird byte orders such as
+Some systems may have even weirder byte orders such as
0x56 0x78 0x12 0x34
0x34 0x12 0x78 0x56
Byteorders C<'1234'> and C<'12345678'> are little-endian, C<'4321'>
and C<'87654321'> are big-endian.
-If you want portable packed integers use the formats C<"n">, C<"N">,
-C<"v">, and C<"V">, their byte endianness and size is known.
+If you want portable packed integers use the formats C<n>, C<N>,
+C<v>, and C<V>, their byte endianness and size is known.
See also L<perlport>.
=item *
C<pack> (and C<unpack>) handle their output and input as flat
sequences of bytes.
+=item *
+
+A comment in a TEMPLATE starts with C<#> and goes to the end of line.
+
+=item *
+
+If TEMPLATE requires more arguments to pack() than actually given, pack()
+assumes additional C<""> arguments. If TEMPLATE requires less arguments
+to pack() than actually given, extra arguments are ignored.
+
=back
Examples:
=item recv SOCKET,SCALAR,LENGTH,FLAGS
Receives a message on a socket. Attempts to receive LENGTH bytes of
-data into variable SCALAR from the specified SOCKET filehandle.
-Actually does a C C<recvfrom>, so that it can return the address of the
-sender. Returns the undefined value if there's an error. SCALAR will
-be grown or shrunk to the length actually read. Takes the same flags
-as the system call of the same name.
-See L<perlipc/"UDP: Message Passing"> for examples.
+data into variable SCALAR from the specified SOCKET filehandle. SCALAR
+will be grown or shrunk to the length actually read. Takes the same
+flags as the system call of the same name. Returns the address of the
+sender if SOCKET's protocol supports this; returns an empty string
+otherwise. If there's an error, returns the undefined value. This call
+is actually implemented in terms of recvfrom(2) system call. See
+L<perlipc/"UDP: Message Passing"> for examples.
=item redo LABEL
C<eval {}>, C<sub {}> or C<do {}>, and should not be used to exit
a grep() or map() operation.
+Note that a block by itself is semantically identical to a loop
+that executes once. Thus C<redo> inside such a block will effectively
+turn it into a looping construct.
+
See also L</continue> for an illustration of how C<last>, C<next>, and
C<redo> work.
open files, or pre-existing files. Check L<perlport> and either the
rename(2) manpage or equivalent system documentation for details.
+=item require VERSION
+
=item require EXPR
=item require
Demands some semantics specified by EXPR, or by C<$_> if EXPR is not
-supplied. If EXPR is numeric, demands that the current version of Perl
-(C<$]> or $PERL_VERSION) be equal or greater than EXPR.
+supplied. If a version number or tuple is specified, or if EXPR is
+numeric, demands that the current version of Perl
+(C<$^V> or C<$]> or $PERL_VERSION) be equal or greater than EXPR.
Otherwise, demands that a library file be included if it hasn't already
been included. The file is included via the do-FILE mechanism, which is
foreach $prefix (@INC) {
$realfilename = "$prefix/$filename";
if (-f $realfilename) {
+ $INC{$filename} = $realfilename;
$result = do $realfilename;
last ITER;
}
}
die "Can't find $filename in \@INC";
}
+ delete $INC{$filename} if $@ || !$result;
die $@ if $@;
die "$filename did not return true value" unless $result;
- $INC{$filename} = $realfilename;
return $result;
}
Sets the current process group for the specified PID, C<0> for the current
process. Will produce a fatal error if used on a machine that doesn't
-implement setpgrp(2). If the arguments are omitted, it defaults to
-C<0,0>. Note that the POSIX version of C<setpgrp> does not accept any
-arguments, so only C<setpgrp(0,0)> is portable. See also C<POSIX::setsid()>.
+implement POSIX setpgid(2) or BSD setpgrp(2). If the arguments are omitted,
+it defaults to C<0,0>. Note that the BSD 4.2 version of C<setpgrp> does not
+accept any arguments, so only C<setpgrp(0,0)> is portable. See also
+C<POSIX::setsid()>.
=item setpriority WHICH,WHO,PRIORITY
array, returns the undefined value. If ARRAY is omitted, shifts the
C<@_> array within the lexical scope of subroutines and formats, and the
C<@ARGV> array at file scopes or within the lexical scopes established by
-the C<eval ''>, C<BEGIN {}>, C<END {}>, and C<INIT {}> constructs.
+the C<eval ''>, C<BEGIN {}>, C<INIT {}>, C<CHECK {}>, and C<END {}>
+constructs.
+
See also C<unshift>, C<push>, and C<pop>. C<Shift()> and C<unshift> do the
same thing to the left end of an array that C<pop> and C<push> do to the
right end.
of a SUBNAME, you can provide a BLOCK as an anonymous, in-line sort
subroutine.
-In the interests of efficiency the normal calling code for subroutines is
-bypassed, with the following effects: the subroutine may not be a
-recursive subroutine, and the two elements to be compared are passed into
-the subroutine not via C<@_> but as the package global variables $a and
-$b (see example below). They are passed by reference, so don't
-modify $a and $b. And don't try to declare them as lexicals either.
+If the subroutine's prototype is C<($$)>, the elements to be compared
+are passed by reference in C<@_>, as for a normal subroutine. If not,
+the normal calling code for subroutines is bypassed in the interests of
+efficiency, and the elements to be compared are passed into the subroutine
+as the package global variables $a and $b (see example below). Note that
+in the latter case, it is usually counter-productive to declare $a and
+$b as lexicals.
+
+In either case, the subroutine may not be recursive. The values to be
+compared are always passed by reference, so don't modify them.
You also cannot exit out of the sort block or subroutine using any of the
loop control operators described in L<perlsyn> or with C<goto>.
||
$a->[2] cmp $b->[2]
} map { [$_, /=(\d+)/, uc($_)] } @old;
+
+ # using a prototype allows you to use any comparison subroutine
+ # as a sort subroutine (including other package's subroutines)
+ package other;
+ sub backwards ($$) { $_[1] cmp $_[0]; } # $a and $b are not set here
+
+ package main;
+ @new = sort other::backwards @old;
If you're using strict, you I<must not> declare $a
and $b as lexicals. They are package globals. That means
point in formatted real numbers is affected by the LC_NUMERIC locale.
See L<perllocale>.
-To cope with broken systems that allow the standard locales to be
-overridden by malicious users, the return value may be tainted
-if any of the floating point formats are used and the conversion
-yields something that doesn't look like a normal C-locale floating
-point number. This happens regardless of whether C<use locale> is
-in effect or not.
-
If Perl understands "quads" (64-bit integers) (this requires
either that the platform natively supports quads or that Perl
has been specifically compiled to support quads), the characters
5 gid numeric group ID of file's owner
6 rdev the device identifier (special files only)
7 size total size of file, in bytes
- 8 atime last access time since the epoch
- 9 mtime last modify time since the epoch
- 10 ctime inode change time (NOT creation time!) since the epoch
+ 8 atime last access time in seconds since the epoch
+ 9 mtime last modify time in seconds since the epoch
+ 10 ctime inode change time (NOT creation time!) in seconds since the epoch
11 blksize preferred block size for file system I/O
12 blocks actual number of blocks allocated
print;
}
-In searching for C</\bfoo\b/>, only those locations in C<$_> that contain C<"f">
-will be looked at, because C<"f"> is rarer than C<"o">. In general, this is
+In searching for C</\bfoo\b/>, only those locations in C<$_> that contain C<f>
+will be looked at, because C<f> is rarer than C<o>. In general, this is
a big win except in pathological cases. The only question is whether
it saves you more time than it took to build the linked list in the
first place.
supported by perl: zero means read-only, one means write-only, and two
means read/write. We know that these values do I<not> work under
OS/390 & VM/ESA Unix and on the Macintosh; you probably don't want to
-se them in new code, use thhe constants discussed in the preceding
-paragraph.
+use them in new code.
If the file named by FILENAME does not exist and the C<open> call creates
it (typically because MODE includes the C<O_CREAT> flag), then the value of
Better to omit it. See the perlfunc(1) entry on C<umask> for more
on this.
+Note that C<sysopen> depends on the fdopen() C library function.
+On many UNIX systems, fdopen() is known to fail when file descriptors
+exceed a certain value, typically 255. If you need more file
+descriptors than that, consider rebuilding Perl to use the C<sfio>
+library, or perhaps using the POSIX::open() function.
+
See L<perlopentut> for a kinder, gentler explanation of opening files.
=item sysread FILEHANDLE,SCALAR,LENGTH,OFFSET
=item unpack TEMPLATE,EXPR
C<unpack> does the reverse of C<pack>: it takes a string
-representing a structure and expands it out into a list of values.
+and expands it out into a list of values.
(In scalar context, it returns merely the first value produced.)
+
+The string is broken into chunks described by the TEMPLATE. Each chunk
+is converted separately to a value. Typically, either the string is a result
+of C<pack>, or the bytes of the string represent a C structure of some
+kind.
+
The TEMPLATE has the same format as in the C<pack> function.
Here's a subroutine that does substring:
sub ordinal { unpack("c",$_[0]); } # same as ord()
-In addition, you may prefix a field with a %E<lt>numberE<gt> to indicate that
+In addition to fields allowed in pack(), you may prefix a field with
+a %E<lt>numberE<gt> to indicate that
you want a E<lt>numberE<gt>-bit checksum of the items instead of the items
-themselves. Default is a 16-bit checksum. For example, the following
+themselves. Default is a 16-bit checksum. Checksum is calculated by
+summing numeric values of expanded values (for string fields the sum of
+C<ord($char)> is taken, for bit fields the sum of zeroes and ones).
+
+For example, the following
computes the same number as the System V sum program:
$checksum = do {
$setbits = unpack("%32b*", $selectmask);
-The C<"p"> and C<"P"> formats should be used with care. Since Perl
+The C<p> and C<P> formats should be used with care. Since Perl
has no way of checking whether the value passed to C<unpack()>
corresponds to a valid memory location, passing a pointer value that's
not known to be valid is likely to have disastrous consequences.
+If the repeat count of a field is larger than what the remainder of
+the input string allows, repeat count is decreased. If the input string
+is longer than one described by the TEMPLATE, the rest is ignored.
+
See L</pack> for more examples and notes.
=item untie VARIABLE
except that Module I<must> be a bareword.
-If the first argument to C<use> is a number, it is treated as a version
-number instead of a module name. If the version of the Perl interpreter
-is less than VERSION, then an error message is printed and Perl exits
-immediately. This is often useful if you need to check the current
-Perl version before C<use>ing library modules that have changed in
-incompatible ways from older versions of Perl. (We try not to do
-this more than we have to.)
+If the first argument to C<use> is a number or a version tuple, it is
+treated as a version instead of a module name. If the version
+of the Perl interpreter is less than VERSION, then an error message
+is printed and Perl exits immediately.
+
+ use 5.005_03; # version number
+ use v5.6.0; # version tuple
+
+This is often useful if you need to check the current Perl version before
+C<use>ing library modules that have changed in incompatible ways from
+older versions of Perl. (We try not to do this more than we have to.)
The C<BEGIN> forces the C<require> and C<import> to happen at compile time. The
C<require> makes sure the module is loaded into memory if it hasn't been
=item vec EXPR,OFFSET,BITS
-Treats the string in EXPR as a vector of unsigned integers, and
-returns the value of the bit field specified by OFFSET. BITS
-specifies the number of bits that are reserved for each entry in the
-bit vector. This must be a power of two from 1 to 32 (or 64, if your
-platform supports that).
+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
+that are reserved for each element in the bit vector. This must
+be a power of two from 1 to 32 (or 64, if your platform supports
+that).
+
+If BITS is 8, "elements" coincide with bytes of the input string.
+
+If BITS is 16 or more, bytes of the input string are grouped into chunks
+of size BITS/8, and each group is converted to a number as with
+pack()/unpack() with big-endian formats C<n>/C<N> (and analoguously
+for BITS==64). See L<"pack"> for details.
+
+If bits is 4 or less, the string is broken into bytes, then the bits
+of each byte are broken into 8/BITS groups. Bits of a byte are
+numbered in a little-endian-ish way, as in C<0x01>, C<0x02>,
+C<0x04>, C<0x08>, C<0x10>, C<0x20>, C<0x40>, C<0x80>. For example,
+breaking the single input byte C<chr(0x36)> into two groups gives a list
+C<(0x6, 0x3)>; breaking it into 4 groups gives C<(0x2, 0x1, 0x3, 0x0)>.
C<vec> may also be assigned to, in which case parentheses are needed
to give the expression the correct precedence as in
my $foo = '';
vec($foo, 0, 32) = 0x5065726C; # 'Perl'
+
+ # $foo eq "Perl" eq "\x50\x65\x72\x6C", 32 bits
+ print vec($foo, 0, 8); # prints 80 == 0x50 == ord('P')
+
vec($foo, 2, 16) = 0x5065; # 'PerlPe'
vec($foo, 3, 16) = 0x726C; # 'PerlPerl'
vec($foo, 8, 8) = 0x50; # 'PerlPerlP'
If you know the exact length in bits, it can be used in place of the C<*>.
+Here is an example to illustrate how the bits actually fall in place:
+
+ #!/usr/bin/perl -wl
+
+ print <<'EOT';
+ 0 1 2 3
+ unpack("V",$_) 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, $res
+ .
+ __END__
+
+Regardless of the machine architecture on which it is run, the above
+example should print the following table:
+
+ 0 1 2 3
+ unpack("V",$_) 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
+
=item wait
Behaves like the wait(2) system call on your system: it waits for a child
https://perl5.git.perl.org / perl5.git / blobdiff