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=head1 NAME

perlapi - autogenerated documentation for the perl public API

=head1 DESCRIPTION

This file contains the documentation of the perl public API generated by
embed.pl, specifically a listing of functions, macros, flags, and variables
that may be used by extension writers.  The interfaces of any functions that
are not listed here are subject to change without notice.  For this reason,
blindly using functions listed in proto.h is to be avoided when writing
extensions.

Note that all Perl API global variables must be referenced with the C<PL_>
prefix.  Some macros are provided for compatibility with the older,
unadorned names, but this support may be disabled in a future release.

The listing is alphabetical, case insensitive.


=head1 "Gimme" Values

=over 8

=item GIMME

A backward-compatible version of C<GIMME_V> which can only return
C<G_SCALAR> or C<G_ARRAY>; in a void context, it returns C<G_SCALAR>.
Deprecated.  Use C<GIMME_V> instead.

	U32	GIMME

=for hackers
Found in file op.h

=item GIMME_V

The XSUB-writer's equivalent to Perl's C<wantarray>.  Returns C<G_VOID>,
C<G_SCALAR> or C<G_ARRAY> for void, scalar or list context,
respectively.

	U32	GIMME_V

=for hackers
Found in file op.h

=item G_ARRAY

Used to indicate list context.  See C<GIMME_V>, C<GIMME> and
L<perlcall>.

=for hackers
Found in file cop.h

=item G_DISCARD

Indicates that arguments returned from a callback should be discarded.  See
L<perlcall>.

=for hackers
Found in file cop.h

=item G_EVAL

Used to force a Perl C<eval> wrapper around a callback.  See
L<perlcall>.

=for hackers
Found in file cop.h

=item G_NOARGS

Indicates that no arguments are being sent to a callback.  See
L<perlcall>.

=for hackers
Found in file cop.h

=item G_SCALAR

Used to indicate scalar context.  See C<GIMME_V>, C<GIMME>, and
L<perlcall>.

=for hackers
Found in file cop.h

=item G_VOID

Used to indicate void context.  See C<GIMME_V> and L<perlcall>.

=for hackers
Found in file cop.h


=back

=head1 Array Manipulation Functions

=over 8

=item AvFILL

Same as C<av_len()>.  Deprecated, use C<av_len()> instead.

	int	AvFILL(AV* av)

=for hackers
Found in file av.h

=item av_clear

Clears an array, making it empty.  Does not free the memory used by the
array itself.

	void	av_clear(AV* ar)

=for hackers
Found in file av.c

=item av_delete

Deletes the element indexed by C<key> from the array.  Returns the
deleted element. If C<flags> equals C<G_DISCARD>, the element is freed
and null is returned.

	SV*	av_delete(AV* ar, I32 key, I32 flags)

=for hackers
Found in file av.c

=item av_exists

Returns true if the element indexed by C<key> has been initialized.

This relies on the fact that uninitialized array elements are set to
C<&PL_sv_undef>.

	bool	av_exists(AV* ar, I32 key)

=for hackers
Found in file av.c

=item av_extend

Pre-extend an array.  The C<key> is the index to which the array should be
extended.

	void	av_extend(AV* ar, I32 key)

=for hackers
Found in file av.c

=item av_fetch

Returns the SV at the specified index in the array.  The C<key> is the
index.  If C<lval> is set then the fetch will be part of a store.  Check
that the return value is non-null before dereferencing it to a C<SV*>.

See L<perlguts/"Understanding the Magic of Tied Hashes and Arrays"> for
more information on how to use this function on tied arrays. 

	SV**	av_fetch(AV* ar, I32 key, I32 lval)

=for hackers
Found in file av.c

=item av_fill

Ensure than an array has a given number of elements, equivalent to
Perl's C<$#array = $fill;>.

	void	av_fill(AV* ar, I32 fill)

=for hackers
Found in file av.c

=item av_len

Returns the highest index in the array.  Returns -1 if the array is
empty.

	I32	av_len(AV* ar)

=for hackers
Found in file av.c

=item av_make

Creates a new AV and populates it with a list of SVs.  The SVs are copied
into the array, so they may be freed after the call to av_make.  The new AV
will have a reference count of 1.

	AV*	av_make(I32 size, SV** svp)

=for hackers
Found in file av.c

=item av_pop

Pops an SV off the end of the array.  Returns C<&PL_sv_undef> if the array
is empty.

	SV*	av_pop(AV* ar)

=for hackers
Found in file av.c

=item av_push

Pushes an SV onto the end of the array.  The array will grow automatically
to accommodate the addition.

	void	av_push(AV* ar, SV* val)

=for hackers
Found in file av.c

=item av_shift

Shifts an SV off the beginning of the array.

	SV*	av_shift(AV* ar)

=for hackers
Found in file av.c

=item av_store

Stores an SV in an array.  The array index is specified as C<key>.  The
return value will be NULL if the operation failed or if the value did not
need to be actually stored within the array (as in the case of tied
arrays). Otherwise it can be dereferenced to get the original C<SV*>.  Note
that the caller is responsible for suitably incrementing the reference
count of C<val> before the call, and decrementing it if the function
returned NULL.

See L<perlguts/"Understanding the Magic of Tied Hashes and Arrays"> for
more information on how to use this function on tied arrays.

	SV**	av_store(AV* ar, I32 key, SV* val)

=for hackers
Found in file av.c

=item av_undef

Undefines the array.  Frees the memory used by the array itself.

	void	av_undef(AV* ar)

=for hackers
Found in file av.c

=item av_unshift

Unshift the given number of C<undef> values onto the beginning of the
array.  The array will grow automatically to accommodate the addition.  You
must then use C<av_store> to assign values to these new elements.

	void	av_unshift(AV* ar, I32 num)

=for hackers
Found in file av.c

=item get_av

Returns the AV of the specified Perl array.  If C<create> is set and the
Perl variable does not exist then it will be created.  If C<create> is not
set and the variable does not exist then NULL is returned.

NOTE: the perl_ form of this function is deprecated.

	AV*	get_av(const char* name, I32 create)

=for hackers
Found in file perl.c

=item newAV

Creates a new AV.  The reference count is set to 1.

	AV*	newAV()

=for hackers
Found in file av.c

=item sortsv

Sort an array. Here is an example:

    sortsv(AvARRAY(av), av_len(av)+1, Perl_sv_cmp_locale);

See lib/sort.pm for details about controlling the sorting algorithm.

	void	sortsv(SV ** array, size_t num_elts, SVCOMPARE_t cmp)

=for hackers
Found in file pp_sort.c


=back

=head1 Callback Functions

=over 8

=item call_argv

Performs a callback to the specified Perl sub.  See L<perlcall>.

NOTE: the perl_ form of this function is deprecated.

	I32	call_argv(const char* sub_name, I32 flags, char** argv)

=for hackers
Found in file perl.c

=item call_method

Performs a callback to the specified Perl method.  The blessed object must
be on the stack.  See L<perlcall>.

NOTE: the perl_ form of this function is deprecated.

	I32	call_method(const char* methname, I32 flags)

=for hackers
Found in file perl.c

=item call_pv

Performs a callback to the specified Perl sub.  See L<perlcall>.

NOTE: the perl_ form of this function is deprecated.

	I32	call_pv(const char* sub_name, I32 flags)

=for hackers
Found in file perl.c

=item call_sv

Performs a callback to the Perl sub whose name is in the SV.  See
L<perlcall>.

NOTE: the perl_ form of this function is deprecated.

	I32	call_sv(SV* sv, I32 flags)

=for hackers
Found in file perl.c

=item ENTER

Opening bracket on a callback.  See C<LEAVE> and L<perlcall>.

		ENTER;

=for hackers
Found in file scope.h

=item eval_pv

Tells Perl to C<eval> the given string and return an SV* result.

NOTE: the perl_ form of this function is deprecated.

	SV*	eval_pv(const char* p, I32 croak_on_error)

=for hackers
Found in file perl.c

=item eval_sv

Tells Perl to C<eval> the string in the SV.

NOTE: the perl_ form of this function is deprecated.

	I32	eval_sv(SV* sv, I32 flags)

=for hackers
Found in file perl.c

=item FREETMPS

Closing bracket for temporaries on a callback.  See C<SAVETMPS> and
L<perlcall>.

		FREETMPS;

=for hackers
Found in file scope.h

=item LEAVE

Closing bracket on a callback.  See C<ENTER> and L<perlcall>.

		LEAVE;

=for hackers
Found in file scope.h

=item SAVETMPS

Opening bracket for temporaries on a callback.  See C<FREETMPS> and
L<perlcall>.

		SAVETMPS;

=for hackers
Found in file scope.h


=back

=head1 Character classes

=over 8

=item isALNUM

Returns a boolean indicating whether the C C<char> is an ASCII alphanumeric
character (including underscore) or digit.

	bool	isALNUM(char ch)

=for hackers
Found in file handy.h

=item isALPHA

Returns a boolean indicating whether the C C<char> is an ASCII alphabetic
character.

	bool	isALPHA(char ch)

=for hackers
Found in file handy.h

=item isDIGIT

Returns a boolean indicating whether the C C<char> is an ASCII
digit.

	bool	isDIGIT(char ch)

=for hackers
Found in file handy.h

=item isLOWER

Returns a boolean indicating whether the C C<char> is a lowercase
character.

	bool	isLOWER(char ch)

=for hackers
Found in file handy.h

=item isSPACE

Returns a boolean indicating whether the C C<char> is whitespace.

	bool	isSPACE(char ch)

=for hackers
Found in file handy.h

=item isUPPER

Returns a boolean indicating whether the C C<char> is an uppercase
character.

	bool	isUPPER(char ch)

=for hackers
Found in file handy.h

=item toLOWER

Converts the specified character to lowercase.

	char	toLOWER(char ch)

=for hackers
Found in file handy.h

=item toUPPER

Converts the specified character to uppercase.

	char	toUPPER(char ch)

=for hackers
Found in file handy.h


=back

=head1 Cloning an interpreter

=over 8

=item perl_clone

Create and return a new interpreter by cloning the current one.

perl_clone takes these flags as parameters:

CLONEf_COPY_STACKS - is used to, well, copy the stacks also,
without it we only clone the data and zero the stacks,
with it we copy the stacks and the new perl interpreter is
ready to run at the exact same point as the previous one.
The pseudo-fork code uses COPY_STACKS while the
threads->new doesn't.

CLONEf_KEEP_PTR_TABLE
perl_clone keeps a ptr_table with the pointer of the old
variable as a key and the new variable as a value,
this allows it to check if something has been cloned and not
clone it again but rather just use the value and increase the
refcount. If KEEP_PTR_TABLE is not set then perl_clone will kill
the ptr_table using the function
C<ptr_table_free(PL_ptr_table); PL_ptr_table = NULL;>,
reason to keep it around is if you want to dup some of your own
variable who are outside the graph perl scans, example of this
code is in threads.xs create

CLONEf_CLONE_HOST
This is a win32 thing, it is ignored on unix, it tells perls
win32host code (which is c++) to clone itself, this is needed on
win32 if you want to run two threads at the same time,
if you just want to do some stuff in a separate perl interpreter
and then throw it away and return to the original one,
you don't need to do anything.

	PerlInterpreter*	perl_clone(PerlInterpreter* interp, UV flags)

=for hackers
Found in file sv.c


=back

=head1 CV Manipulation Functions

=over 8

=item CvSTASH

Returns the stash of the CV.

	HV*	CvSTASH(CV* cv)

=for hackers
Found in file cv.h

=item get_cv

Returns the CV of the specified Perl subroutine.  If C<create> is set and
the Perl subroutine does not exist then it will be declared (which has the
same effect as saying C<sub name;>).  If C<create> is not set and the
subroutine does not exist then NULL is returned.

NOTE: the perl_ form of this function is deprecated.

	CV*	get_cv(const char* name, I32 create)

=for hackers
Found in file perl.c


=back

=head1 Embedding Functions

=over 8

=item cv_undef

Clear out all the active components of a CV. This can happen either
by an explicit C<undef &foo>, or by the reference count going to zero.
In the former case, we keep the CvOUTSIDE pointer, so that any anonymous
children can still follow the full lexical scope chain.

	void	cv_undef(CV* cv)

=for hackers
Found in file op.c

=item load_module

Loads the module whose name is pointed to by the string part of name.
Note that the actual module name, not its filename, should be given.
Eg, "Foo::Bar" instead of "Foo/Bar.pm".  flags can be any of
PERL_LOADMOD_DENY, PERL_LOADMOD_NOIMPORT, or PERL_LOADMOD_IMPORT_OPS
(or 0 for no flags). ver, if specified, provides version semantics
similar to C<use Foo::Bar VERSION>.  The optional trailing SV*
arguments can be used to specify arguments to the module's import()
method, similar to C<use Foo::Bar VERSION LIST>.

	void	load_module(U32 flags, SV* name, SV* ver, ...)

=for hackers
Found in file op.c

=item nothreadhook

Stub that provides thread hook for perl_destruct when there are
no threads.

	int	nothreadhook()

=for hackers
Found in file perl.c

=item perl_alloc

Allocates a new Perl interpreter.  See L<perlembed>.

	PerlInterpreter*	perl_alloc()

=for hackers
Found in file perl.c

=item perl_construct

Initializes a new Perl interpreter.  See L<perlembed>.

	void	perl_construct(PerlInterpreter* interp)

=for hackers
Found in file perl.c

=item perl_destruct

Shuts down a Perl interpreter.  See L<perlembed>.

	int	perl_destruct(PerlInterpreter* interp)

=for hackers
Found in file perl.c

=item perl_free

Releases a Perl interpreter.  See L<perlembed>.

	void	perl_free(PerlInterpreter* interp)

=for hackers
Found in file perl.c

=item perl_parse

Tells a Perl interpreter to parse a Perl script.  See L<perlembed>.

	int	perl_parse(PerlInterpreter* interp, XSINIT_t xsinit, int argc, char** argv, char** env)

=for hackers
Found in file perl.c

=item perl_run

Tells a Perl interpreter to run.  See L<perlembed>.

	int	perl_run(PerlInterpreter* interp)

=for hackers
Found in file perl.c

=item require_pv

Tells Perl to C<require> the file named by the string argument.  It is
analogous to the Perl code C<eval "require '$file'">.  It's even
implemented that way; consider using load_module instead.

NOTE: the perl_ form of this function is deprecated.

	void	require_pv(const char* pv)

=for hackers
Found in file perl.c


=back

=head1 Functions in file pp_pack.c


=over 8

=item packlist

The engine implementing pack() Perl function.

	void	packlist(SV *cat, char *pat, char *patend, SV **beglist, SV **endlist)

=for hackers
Found in file pp_pack.c

=item pack_cat

The engine implementing pack() Perl function. Note: parameters next_in_list and
flags are not used. This call should not be used; use packlist instead.

	void	pack_cat(SV *cat, char *pat, char *patend, SV **beglist, SV **endlist, SV ***next_in_list, U32 flags)

=for hackers
Found in file pp_pack.c

=item unpackstring

The engine implementing unpack() Perl function. C<unpackstring> puts the
extracted list items on the stack and returns the number of elements.
Issue C<PUTBACK> before and C<SPAGAIN> after the call to this function.

	I32	unpackstring(char *pat, char *patend, char *s, char *strend, U32 flags)

=for hackers
Found in file pp_pack.c

=item unpack_str

The engine implementing unpack() Perl function. Note: parameters strbeg, new_s
and ocnt are not used. This call should not be used, use unpackstring instead.

	I32	unpack_str(char *pat, char *patend, char *s, char *strbeg, char *strend, char **new_s, I32 ocnt, U32 flags)

=for hackers
Found in file pp_pack.c


=back

=head1 Global Variables

=over 8

=item PL_modglobal

C<PL_modglobal> is a general purpose, interpreter global HV for use by
extensions that need to keep information on a per-interpreter basis.
In a pinch, it can also be used as a symbol table for extensions
to share data among each other.  It is a good idea to use keys
prefixed by the package name of the extension that owns the data.

	HV*	PL_modglobal

=for hackers
Found in file intrpvar.h

=item PL_na

A convenience variable which is typically used with C<SvPV> when one
doesn't care about the length of the string.  It is usually more efficient
to either declare a local variable and use that instead or to use the
C<SvPV_nolen> macro.

	STRLEN	PL_na

=for hackers
Found in file thrdvar.h

=item PL_sv_no

This is the C<false> SV.  See C<PL_sv_yes>.  Always refer to this as
C<&PL_sv_no>.

	SV	PL_sv_no

=for hackers
Found in file intrpvar.h

=item PL_sv_undef

This is the C<undef> SV.  Always refer to this as C<&PL_sv_undef>.

	SV	PL_sv_undef

=for hackers
Found in file intrpvar.h

=item PL_sv_yes

This is the C<true> SV.  See C<PL_sv_no>.  Always refer to this as
C<&PL_sv_yes>.

	SV	PL_sv_yes

=for hackers
Found in file intrpvar.h


=back

=head1 GV Functions

=over 8

=item GvSV

Return the SV from the GV.

	SV*	GvSV(GV* gv)

=for hackers
Found in file gv.h

=item gv_fetchmeth

Returns the glob with the given C<name> and a defined subroutine or
C<NULL>.  The glob lives in the given C<stash>, or in the stashes
accessible via @ISA and UNIVERSAL::.

The argument C<level> should be either 0 or -1.  If C<level==0>, as a
side-effect creates a glob with the given C<name> in the given C<stash>
which in the case of success contains an alias for the subroutine, and sets
up caching info for this glob.  Similarly for all the searched stashes.

This function grants C<"SUPER"> token as a postfix of the stash name. The
GV returned from C<gv_fetchmeth> may be a method cache entry, which is not
visible to Perl code.  So when calling C<call_sv>, you should not use
the GV directly; instead, you should use the method's CV, which can be
obtained from the GV with the C<GvCV> macro.

	GV*	gv_fetchmeth(HV* stash, const char* name, STRLEN len, I32 level)

=for hackers
Found in file gv.c

=item gv_fetchmethod

See L<gv_fetchmethod_autoload>.

	GV*	gv_fetchmethod(HV* stash, const char* name)

=for hackers
Found in file gv.c

=item gv_fetchmethod_autoload

Returns the glob which contains the subroutine to call to invoke the method
on the C<stash>.  In fact in the presence of autoloading this may be the
glob for "AUTOLOAD".  In this case the corresponding variable $AUTOLOAD is
already setup.

The third parameter of C<gv_fetchmethod_autoload> determines whether
AUTOLOAD lookup is performed if the given method is not present: non-zero
means yes, look for AUTOLOAD; zero means no, don't look for AUTOLOAD.
Calling C<gv_fetchmethod> is equivalent to calling C<gv_fetchmethod_autoload>
with a non-zero C<autoload> parameter.

These functions grant C<"SUPER"> token as a prefix of the method name. Note
that if you want to keep the returned glob for a long time, you need to
check for it being "AUTOLOAD", since at the later time the call may load a
different subroutine due to $AUTOLOAD changing its value. Use the glob
created via a side effect to do this.

These functions have the same side-effects and as C<gv_fetchmeth> with
C<level==0>.  C<name> should be writable if contains C<':'> or C<'
''>. The warning against passing the GV returned by C<gv_fetchmeth> to
C<call_sv> apply equally to these functions.

	GV*	gv_fetchmethod_autoload(HV* stash, const char* name, I32 autoload)

=for hackers
Found in file gv.c

=item gv_fetchmeth_autoload

Same as gv_fetchmeth(), but looks for autoloaded subroutines too.
Returns a glob for the subroutine.

For an autoloaded subroutine without a GV, will create a GV even
if C<level < 0>.  For an autoloaded subroutine without a stub, GvCV()
of the result may be zero.

	GV*	gv_fetchmeth_autoload(HV* stash, const char* name, STRLEN len, I32 level)

=for hackers
Found in file gv.c

=item gv_stashpv

Returns a pointer to the stash for a specified package.  C<name> should
be a valid UTF-8 string.  If C<create> is set then the package will be
created if it does not already exist.  If C<create> is not set and the
package does not exist then NULL is returned.

	HV*	gv_stashpv(const char* name, I32 create)

=for hackers
Found in file gv.c

=item gv_stashsv

Returns a pointer to the stash for a specified package, which must be a
valid UTF-8 string.  See C<gv_stashpv>.

	HV*	gv_stashsv(SV* sv, I32 create)

=for hackers
Found in file gv.c


=back

=head1 Handy Values

=over 8

=item Nullav

Null AV pointer.

=for hackers
Found in file av.h

=item Nullch

Null character pointer.

=for hackers
Found in file handy.h

=item Nullcv

Null CV pointer.

=for hackers
Found in file cv.h

=item Nullhv

Null HV pointer.

=for hackers
Found in file hv.h

=item Nullsv

Null SV pointer.

=for hackers
Found in file handy.h


=back

=head1 Hash Manipulation Functions

=over 8

=item get_hv

Returns the HV of the specified Perl hash.  If C<create> is set and the
Perl variable does not exist then it will be created.  If C<create> is not
set and the variable does not exist then NULL is returned.

NOTE: the perl_ form of this function is deprecated.

	HV*	get_hv(const char* name, I32 create)

=for hackers
Found in file perl.c

=item HEf_SVKEY

This flag, used in the length slot of hash entries and magic structures,
specifies the structure contains an C<SV*> pointer where a C<char*> pointer
is to be expected. (For information only--not to be used).

=for hackers
Found in file hv.h

=item HeHASH

Returns the computed hash stored in the hash entry.

	U32	HeHASH(HE* he)

=for hackers
Found in file hv.h

=item HeKEY

Returns the actual pointer stored in the key slot of the hash entry. The
pointer may be either C<char*> or C<SV*>, depending on the value of
C<HeKLEN()>.  Can be assigned to.  The C<HePV()> or C<HeSVKEY()> macros are
usually preferable for finding the value of a key.

	void*	HeKEY(HE* he)

=for hackers
Found in file hv.h

=item HeKLEN

If this is negative, and amounts to C<HEf_SVKEY>, it indicates the entry
holds an C<SV*> key.  Otherwise, holds the actual length of the key.  Can
be assigned to. The C<HePV()> macro is usually preferable for finding key
lengths.

	STRLEN	HeKLEN(HE* he)

=for hackers
Found in file hv.h

=item HePV

Returns the key slot of the hash entry as a C<char*> value, doing any
necessary dereferencing of possibly C<SV*> keys.  The length of the string
is placed in C<len> (this is a macro, so do I<not> use C<&len>).  If you do
not care about what the length of the key is, you may use the global
variable C<PL_na>, though this is rather less efficient than using a local
variable.  Remember though, that hash keys in perl are free to contain
embedded nulls, so using C<strlen()> or similar is not a good way to find
the length of hash keys. This is very similar to the C<SvPV()> macro
described elsewhere in this document.

	char*	HePV(HE* he, STRLEN len)

=for hackers
Found in file hv.h

=item HeSVKEY

Returns the key as an C<SV*>, or C<Nullsv> if the hash entry does not
contain an C<SV*> key.

	SV*	HeSVKEY(HE* he)

=for hackers
Found in file hv.h

=item HeSVKEY_force

Returns the key as an C<SV*>.  Will create and return a temporary mortal
C<SV*> if the hash entry contains only a C<char*> key.

	SV*	HeSVKEY_force(HE* he)

=for hackers
Found in file hv.h

=item HeSVKEY_set

Sets the key to a given C<SV*>, taking care to set the appropriate flags to
indicate the presence of an C<SV*> key, and returns the same
C<SV*>.

	SV*	HeSVKEY_set(HE* he, SV* sv)

=for hackers
Found in file hv.h

=item HeVAL

Returns the value slot (type C<SV*>) stored in the hash entry.

	SV*	HeVAL(HE* he)

=for hackers
Found in file hv.h

=item HvNAME

Returns the package name of a stash.  See C<SvSTASH>, C<CvSTASH>.

	char*	HvNAME(HV* stash)

=for hackers
Found in file hv.h

=item hv_assert

Check that a hash is in an internally consistent state.

	void	hv_assert(HV* tb)

=for hackers
Found in file hv.c

=item hv_clear

Clears a hash, making it empty.

	void	hv_clear(HV* tb)

=for hackers
Found in file hv.c

=item hv_clear_placeholders

Clears any placeholders from a hash.  If a restricted hash has any of its keys
marked as readonly and the key is subsequently deleted, the key is not actually
deleted but is marked by assigning it a value of &PL_sv_placeholder.  This tags
it so it will be ignored by future operations such as iterating over the hash,
but will still allow the hash to have a value reassigned to the key at some
future point.  This function clears any such placeholder keys from the hash.
See Hash::Util::lock_keys() for an example of its use.

	void	hv_clear_placeholders(HV* hb)

=for hackers
Found in file hv.c

=item hv_delete

Deletes a key/value pair in the hash.  The value SV is removed from the
hash and returned to the caller.  The C<klen> is the length of the key.
The C<flags> value will normally be zero; if set to G_DISCARD then NULL
will be returned.

	SV*	hv_delete(HV* tb, const char* key, I32 klen, I32 flags)

=for hackers
Found in file hv.c

=item hv_delete_ent

Deletes a key/value pair in the hash.  The value SV is removed from the
hash and returned to the caller.  The C<flags> value will normally be zero;
if set to G_DISCARD then NULL will be returned.  C<hash> can be a valid
precomputed hash value, or 0 to ask for it to be computed.

	SV*	hv_delete_ent(HV* tb, SV* key, I32 flags, U32 hash)

=for hackers
Found in file hv.c

=item hv_exists

Returns a boolean indicating whether the specified hash key exists.  The
C<klen> is the length of the key.

	bool	hv_exists(HV* tb, const char* key, I32 klen)

=for hackers
Found in file hv.c

=item hv_exists_ent

Returns a boolean indicating whether the specified hash key exists. C<hash>
can be a valid precomputed hash value, or 0 to ask for it to be
computed.

	bool	hv_exists_ent(HV* tb, SV* key, U32 hash)

=for hackers
Found in file hv.c

=item hv_fetch

Returns the SV which corresponds to the specified key in the hash.  The
C<klen> is the length of the key.  If C<lval> is set then the fetch will be
part of a store.  Check that the return value is non-null before
dereferencing it to an C<SV*>.

See L<perlguts/"Understanding the Magic of Tied Hashes and Arrays"> for more
information on how to use this function on tied hashes.

	SV**	hv_fetch(HV* tb, const char* key, I32 klen, I32 lval)

=for hackers
Found in file hv.c

=item hv_fetch_ent

Returns the hash entry which corresponds to the specified key in the hash.
C<hash> must be a valid precomputed hash number for the given C<key>, or 0
if you want the function to compute it.  IF C<lval> is set then the fetch
will be part of a store.  Make sure the return value is non-null before
accessing it.  The return value when C<tb> is a tied hash is a pointer to a
static location, so be sure to make a copy of the structure if you need to
store it somewhere.

See L<perlguts/"Understanding the Magic of Tied Hashes and Arrays"> for more
information on how to use this function on tied hashes.

	HE*	hv_fetch_ent(HV* tb, SV* key, I32 lval, U32 hash)

=for hackers
Found in file hv.c

=item hv_iterinit

Prepares a starting point to traverse a hash table.  Returns the number of
keys in the hash (i.e. the same as C<HvKEYS(tb)>).  The return value is
currently only meaningful for hashes without tie magic.

NOTE: Before version 5.004_65, C<hv_iterinit> used to return the number of
hash buckets that happen to be in use.  If you still need that esoteric
value, you can get it through the macro C<HvFILL(tb)>.


	I32	hv_iterinit(HV* tb)

=for hackers
Found in file hv.c

=item hv_iterkey

Returns the key from the current position of the hash iterator.  See
C<hv_iterinit>.

	char*	hv_iterkey(HE* entry, I32* retlen)

=for hackers
Found in file hv.c

=item hv_iterkeysv

Returns the key as an C<SV*> from the current position of the hash
iterator.  The return value will always be a mortal copy of the key.  Also
see C<hv_iterinit>.

	SV*	hv_iterkeysv(HE* entry)

=for hackers
Found in file hv.c

=item hv_iternext

Returns entries from a hash iterator.  See C<hv_iterinit>.

You may call C<hv_delete> or C<hv_delete_ent> on the hash entry that the
iterator currently points to, without losing your place or invalidating your
iterator.  Note that in this case the current entry is deleted from the hash
with your iterator holding the last reference to it.  Your iterator is flagged
to free the entry on the next call to C<hv_iternext>, so you must not discard
your iterator immediately else the entry will leak - call C<hv_iternext> to
trigger the resource deallocation.

	HE*	hv_iternext(HV* tb)

=for hackers
Found in file hv.c

=item hv_iternextsv

Performs an C<hv_iternext>, C<hv_iterkey>, and C<hv_iterval> in one
operation.

	SV*	hv_iternextsv(HV* hv, char** key, I32* retlen)

=for hackers
Found in file hv.c

=item hv_iternext_flags

Returns entries from a hash iterator.  See C<hv_iterinit> and C<hv_iternext>.
The C<flags> value will normally be zero; if HV_ITERNEXT_WANTPLACEHOLDERS is
set the placeholders keys (for restricted hashes) will be returned in addition
to normal keys. By default placeholders are automatically skipped over.
Currently a placeholder is implemented with a value that is
C<&Perl_sv_placeholder>. Note that the implementation of placeholders and
restricted hashes may change, and the implementation currently is
insufficiently abstracted for any change to be tidy.

NOTE: this function is experimental and may change or be
removed without notice.

	HE*	hv_iternext_flags(HV* tb, I32 flags)

=for hackers
Found in file hv.c

=item hv_iterval

Returns the value from the current position of the hash iterator.  See
C<hv_iterkey>.

	SV*	hv_iterval(HV* tb, HE* entry)

=for hackers
Found in file hv.c

=item hv_magic

Adds magic to a hash.  See C<sv_magic>.

	void	hv_magic(HV* hv, GV* gv, int how)

=for hackers
Found in file hv.c

=item hv_scalar

Evaluates the hash in scalar context and returns the result. Handles magic when the hash is tied.

	SV*	hv_scalar(HV* hv)

=for hackers
Found in file hv.c

=item hv_store

Stores an SV in a hash.  The hash key is specified as C<key> and C<klen> is
the length of the key.  The C<hash> parameter is the precomputed hash
value; if it is zero then Perl will compute it.  The return value will be
NULL if the operation failed or if the value did not need to be actually
stored within the hash (as in the case of tied hashes).  Otherwise it can
be dereferenced to get the original C<SV*>.  Note that the caller is
responsible for suitably incrementing the reference count of C<val> before
the call, and decrementing it if the function returned NULL.  Effectively
a successful hv_store takes ownership of one reference to C<val>.  This is
usually what you want; a newly created SV has a reference count of one, so
if all your code does is create SVs then store them in a hash, hv_store
will own the only reference to the new SV, and your code doesn't need to do
anything further to tidy up.  hv_store is not implemented as a call to
hv_store_ent, and does not create a temporary SV for the key, so if your
key data is not already in SV form then use hv_store in preference to
hv_store_ent.

See L<perlguts/"Understanding the Magic of Tied Hashes and Arrays"> for more
information on how to use this function on tied hashes.

	SV**	hv_store(HV* tb, const char* key, I32 klen, SV* val, U32 hash)

=for hackers
Found in file hv.c

=item hv_store_ent

Stores C<val> in a hash.  The hash key is specified as C<key>.  The C<hash>
parameter is the precomputed hash value; if it is zero then Perl will
compute it.  The return value is the new hash entry so created.  It will be
NULL if the operation failed or if the value did not need to be actually
stored within the hash (as in the case of tied hashes).  Otherwise the
contents of the return value can be accessed using the C<He?> macros
described here.  Note that the caller is responsible for suitably
incrementing the reference count of C<val> before the call, and
decrementing it if the function returned NULL.  Effectively a successful
hv_store_ent takes ownership of one reference to C<val>.  This is
usually what you want; a newly created SV has a reference count of one, so
if all your code does is create SVs then store them in a hash, hv_store
will own the only reference to the new SV, and your code doesn't need to do
anything further to tidy up.  Note that hv_store_ent only reads the C<key>;
unlike C<val> it does not take ownership of it, so maintaining the correct
reference count on C<key> is entirely the caller's responsibility.  hv_store
is not implemented as a call to hv_store_ent, and does not create a temporary
SV for the key, so if your key data is not already in SV form then use
hv_store in preference to hv_store_ent.

See L<perlguts/"Understanding the Magic of Tied Hashes and Arrays"> for more
information on how to use this function on tied hashes.

	HE*	hv_store_ent(HV* tb, SV* key, SV* val, U32 hash)

=for hackers
Found in file hv.c

=item hv_undef

Undefines the hash.

	void	hv_undef(HV* tb)

=for hackers
Found in file hv.c

=item newHV

Creates a new HV.  The reference count is set to 1.

	HV*	newHV()

=for hackers
Found in file hv.c


=back

=head1 Magical Functions

=over 8

=item mg_clear

Clear something magical that the SV represents.  See C<sv_magic>.

	int	mg_clear(SV* sv)

=for hackers
Found in file mg.c

=item mg_copy

Copies the magic from one SV to another.  See C<sv_magic>.

	int	mg_copy(SV* sv, SV* nsv, const char* key, I32 klen)

=for hackers
Found in file mg.c

=item mg_find

Finds the magic pointer for type matching the SV.  See C<sv_magic>.

	MAGIC*	mg_find(SV* sv, int type)

=for hackers
Found in file mg.c

=item mg_free

Free any magic storage used by the SV.  See C<sv_magic>.

	int	mg_free(SV* sv)

=for hackers
Found in file mg.c

=item mg_get

Do magic after a value is retrieved from the SV.  See C<sv_magic>.

	int	mg_get(SV* sv)

=for hackers
Found in file mg.c

=item mg_length

Report on the SV's length.  See C<sv_magic>.

	U32	mg_length(SV* sv)

=for hackers
Found in file mg.c

=item mg_magical

Turns on the magical status of an SV.  See C<sv_magic>.

	void	mg_magical(SV* sv)

=for hackers
Found in file mg.c

=item mg_set

Do magic after a value is assigned to the SV.  See C<sv_magic>.

	int	mg_set(SV* sv)

=for hackers
Found in file mg.c

=item SvGETMAGIC

Invokes C<mg_get> on an SV if it has 'get' magic.  This macro evaluates its
argument more than once.

	void	SvGETMAGIC(SV* sv)

=for hackers
Found in file sv.h

=item SvLOCK

Arranges for a mutual exclusion lock to be obtained on sv if a suitable module
has been loaded.

	void	SvLOCK(SV* sv)

=for hackers
Found in file sv.h

=item SvSETMAGIC

Invokes C<mg_set> on an SV if it has 'set' magic.  This macro evaluates its
argument more than once.

	void	SvSETMAGIC(SV* sv)

=for hackers
Found in file sv.h

=item SvSetMagicSV

Like C<SvSetSV>, but does any set magic required afterwards.

	void	SvSetMagicSV(SV* dsb, SV* ssv)

=for hackers
Found in file sv.h

=item SvSetMagicSV_nosteal

Like C<SvSetSV_nosteal>, but does any set magic required afterwards.

	void	SvSetMagicSV_nosteal(SV* dsv, SV* ssv)

=for hackers
Found in file sv.h

=item SvSetSV

Calls C<sv_setsv> if dsv is not the same as ssv.  May evaluate arguments
more than once.

	void	SvSetSV(SV* dsb, SV* ssv)

=for hackers
Found in file sv.h

=item SvSetSV_nosteal

Calls a non-destructive version of C<sv_setsv> if dsv is not the same as
ssv. May evaluate arguments more than once.

	void	SvSetSV_nosteal(SV* dsv, SV* ssv)

=for hackers
Found in file sv.h

=item SvSHARE

Arranges for sv to be shared between threads if a suitable module
has been loaded.

	void	SvSHARE(SV* sv)

=for hackers
Found in file sv.h

=item SvUNLOCK

Releases a mutual exclusion lock on sv if a suitable module
has been loaded.

	void	SvUNLOCK(SV* sv)

=for hackers
Found in file sv.h


=back

=head1 Memory Management

=over 8

=item Copy

The XSUB-writer's interface to the C C<memcpy> function.  The C<src> is the
source, C<dest> is the destination, C<nitems> is the number of items, and C<type> is
the type.  May fail on overlapping copies.  See also C<Move>.

	void	Copy(void* src, void* dest, int nitems, type)

=for hackers
Found in file handy.h

=item CopyD

Like C<Copy> but returns dest. Useful for encouraging compilers to tail-call
optimise.

	void *	CopyD(void* src, void* dest, int nitems, type)

=for hackers
Found in file handy.h

=item Move

The XSUB-writer's interface to the C C<memmove> function.  The C<src> is the
source, C<dest> is the destination, C<nitems> is the number of items, and C<type> is
the type.  Can do overlapping moves.  See also C<Copy>.

	void	Move(void* src, void* dest, int nitems, type)

=for hackers
Found in file handy.h

=item MoveD

Like C<Move> but returns dest. Useful for encouraging compilers to tail-call
optimise.

	void *	MoveD(void* src, void* dest, int nitems, type)

=for hackers
Found in file handy.h

=item New

The XSUB-writer's interface to the C C<malloc> function.

	void	New(int id, void* ptr, int nitems, type)

=for hackers
Found in file handy.h

=item Newc

The XSUB-writer's interface to the C C<malloc> function, with
cast.

	void	Newc(int id, void* ptr, int nitems, type, cast)

=for hackers
Found in file handy.h

=item Newz

The XSUB-writer's interface to the C C<malloc> function.  The allocated
memory is zeroed with C<memzero>.

	void	Newz(int id, void* ptr, int nitems, type)

=for hackers
Found in file handy.h

=item Poison

Fill up memory with a pattern (byte 0xAB over and over again) that
hopefully catches attempts to access uninitialized memory.

	void	Poison(void* dest, int nitems, type)

=for hackers
Found in file handy.h

=item Renew

The XSUB-writer's interface to the C C<realloc> function.

	void	Renew(void* ptr, int nitems, type)

=for hackers
Found in file handy.h

=item Renewc

The XSUB-writer's interface to the C C<realloc> function, with
cast.

	void	Renewc(void* ptr, int nitems, type, cast)

=for hackers
Found in file handy.h

=item Safefree

The XSUB-writer's interface to the C C<free> function.

	void	Safefree(void* ptr)

=for hackers
Found in file handy.h

=item savepv

Perl's version of C<strdup()>. Returns a pointer to a newly allocated
string which is a duplicate of C<pv>. The size of the string is
determined by C<strlen()>. The memory allocated for the new string can
be freed with the C<Safefree()> function.

	char*	savepv(const char* pv)

=for hackers
Found in file util.c

=item savepvn

Perl's version of what C<strndup()> would be if it existed. Returns a
pointer to a newly allocated string which is a duplicate of the first
C<len> bytes from C<pv>. The memory allocated for the new string can be
freed with the C<Safefree()> function.

	char*	savepvn(const char* pv, I32 len)

=for hackers
Found in file util.c

=item savesharedpv

A version of C<savepv()> which allocates the duplicate string in memory
which is shared between threads.

	char*	savesharedpv(const char* pv)

=for hackers
Found in file util.c

=item StructCopy

This is an architecture-independent macro to copy one structure to another.

	void	StructCopy(type src, type dest, type)

=for hackers
Found in file handy.h

=item Zero

The XSUB-writer's interface to the C C<memzero> function.  The C<dest> is the
destination, C<nitems> is the number of items, and C<type> is the type.

	void	Zero(void* dest, int nitems, type)

=for hackers
Found in file handy.h

=item ZeroD

Like C<Zero> but returns dest. Useful for encouraging compilers to tail-call
optimise.

	void *	ZeroD(void* dest, int nitems, type)

=for hackers
Found in file handy.h


=back

=head1 Miscellaneous Functions

=over 8

=item fbm_compile

Analyses the string in order to make fast searches on it using fbm_instr()
-- the Boyer-Moore algorithm.

	void	fbm_compile(SV* sv, U32 flags)

=for hackers
Found in file util.c

=item fbm_instr

Returns the location of the SV in the string delimited by C<str> and
C<strend>.  It returns C<Nullch> if the string can't be found.  The C<sv>
does not have to be fbm_compiled, but the search will not be as fast
then.

	char*	fbm_instr(unsigned char* big, unsigned char* bigend, SV* littlesv, U32 flags)

=for hackers
Found in file util.c

=item form

Takes a sprintf-style format pattern and conventional
(non-SV) arguments and returns the formatted string.

    (char *) Perl_form(pTHX_ const char* pat, ...)

can be used any place a string (char *) is required:

    char * s = Perl_form("%d.%d",major,minor);

Uses a single private buffer so if you want to format several strings you
must explicitly copy the earlier strings away (and free the copies when you
are done).

	char*	form(const char* pat, ...)

=for hackers
Found in file util.c

=item getcwd_sv

Fill the sv with current working directory

	int	getcwd_sv(SV* sv)

=for hackers
Found in file util.c

=item new_version

Returns a new version object based on the passed in SV:

    SV *sv = new_version(SV *ver);

Does not alter the passed in ver SV.  See "upg_version" if you
want to upgrade the SV.

	SV*	new_version(SV *ver)

=for hackers
Found in file util.c

=item scan_version

Returns a pointer to the next character after the parsed
version string, as well as upgrading the passed in SV to
an RV.

Function must be called with an already existing SV like

    sv = newSV(0);
    s = scan_version(s,SV *sv, bool qv);

Performs some preprocessing to the string to ensure that
it has the correct characteristics of a version.  Flags the
object if it contains an underscore (which denotes this
is a alpha version).  The boolean qv denotes that the version
should be interpreted as if it had multiple decimals, even if
it doesn't.

	char*	scan_version(char *vstr, SV *sv, bool qv)

=for hackers
Found in file util.c

=item strEQ

Test two strings to see if they are equal.  Returns true or false.

	bool	strEQ(char* s1, char* s2)

=for hackers
Found in file handy.h

=item strGE

Test two strings to see if the first, C<s1>, is greater than or equal to
the second, C<s2>.  Returns true or false.

	bool	strGE(char* s1, char* s2)

=for hackers
Found in file handy.h

=item strGT

Test two strings to see if the first, C<s1>, is greater than the second,
C<s2>.  Returns true or false.

	bool	strGT(char* s1, char* s2)

=for hackers
Found in file handy.h

=item strLE

Test two strings to see if the first, C<s1>, is less than or equal to the
second, C<s2>.  Returns true or false.

	bool	strLE(char* s1, char* s2)

=for hackers
Found in file handy.h

=item strLT

Test two strings to see if the first, C<s1>, is less than the second,
C<s2>.  Returns true or false.

	bool	strLT(char* s1, char* s2)

=for hackers
Found in file handy.h

=item strNE

Test two strings to see if they are different.  Returns true or
false.

	bool	strNE(char* s1, char* s2)

=for hackers
Found in file handy.h

=item strnEQ

Test two strings to see if they are equal.  The C<len> parameter indicates
the number of bytes to compare.  Returns true or false. (A wrapper for
C<strncmp>).

	bool	strnEQ(char* s1, char* s2, STRLEN len)

=for hackers
Found in file handy.h

=item strnNE

Test two strings to see if they are different.  The C<len> parameter
indicates the number of bytes to compare.  Returns true or false. (A
wrapper for C<strncmp>).

	bool	strnNE(char* s1, char* s2, STRLEN len)

=for hackers
Found in file handy.h

=item sv_nolocking

Dummy routine which "locks" an SV when there is no locking module present.
Exists to avoid test for a NULL function pointer and because it could potentially warn under
some level of strict-ness.

	void	sv_nolocking(SV *)

=for hackers
Found in file util.c

=item sv_nosharing

Dummy routine which "shares" an SV when there is no sharing module present.
Exists to avoid test for a NULL function pointer and because it could potentially warn under
some level of strict-ness.

	void	sv_nosharing(SV *)

=for hackers
Found in file util.c

=item sv_nounlocking

Dummy routine which "unlocks" an SV when there is no locking module present.
Exists to avoid test for a NULL function pointer and because it could potentially warn under
some level of strict-ness.

	void	sv_nounlocking(SV *)

=for hackers
Found in file util.c

=item upg_version

In-place upgrade of the supplied SV to a version object.

    SV *sv = upg_version(SV *sv);

Returns a pointer to the upgraded SV.

	SV*	upg_version(SV *ver)

=for hackers
Found in file util.c

=item vcmp

Version object aware cmp.  Both operands must already have been 
converted into version objects.

	int	vcmp(SV *lvs, SV *rvs)

=for hackers
Found in file util.c

=item vnormal

Accepts a version object and returns the normalized string
representation.  Call like:

    sv = vnormal(rv);

NOTE: you can pass either the object directly or the SV
contained within the RV.

	SV*	vnormal(SV *vs)

=for hackers
Found in file util.c

=item vnumify

Accepts a version object and returns the normalized floating
point representation.  Call like:

    sv = vnumify(rv);

NOTE: you can pass either the object directly or the SV
contained within the RV.

	SV*	vnumify(SV *vs)

=for hackers
Found in file util.c

=item vstringify

In order to maintain maximum compatibility with earlier versions
of Perl, this function will return either the floating point
notation or the multiple dotted notation, depending on whether
the original version contained 1 or more dots, respectively

	SV*	vstringify(SV *vs)

=for hackers
Found in file util.c


=back

=head1 Numeric functions

=over 8

=item grok_bin

converts a string representing a binary number to numeric form.

On entry I<start> and I<*len> give the string to scan, I<*flags> gives
conversion flags, and I<result> should be NULL or a pointer to an NV.
The scan stops at the end of the string, or the first invalid character.
Unless C<PERL_SCAN_SILENT_ILLDIGIT> is set in I<*flags>, encountering an
invalid character will also trigger a warning.
On return I<*len> is set to the length of the scanned string,
and I<*flags> gives output flags.

If the value is <= UV_MAX it is returned as a UV, the output flags are clear,
and nothing is written to I<*result>. If the value is > UV_MAX C<grok_bin>
returns UV_MAX, sets C<PERL_SCAN_GREATER_THAN_UV_MAX> in the output flags,
and writes the value to I<*result> (or the value is discarded if I<result>
is NULL).

The binary number may optionally be prefixed with "0b" or "b" unless
C<PERL_SCAN_DISALLOW_PREFIX> is set in I<*flags> on entry. If
C<PERL_SCAN_ALLOW_UNDERSCORES> is set in I<*flags> then the binary
number may use '_' characters to separate digits.

	UV	grok_bin(char* start, STRLEN* len, I32* flags, NV *result)

=for hackers
Found in file numeric.c

=item grok_hex

converts a string representing a hex number to numeric form.

On entry I<start> and I<*len> give the string to scan, I<*flags> gives
conversion flags, and I<result> should be NULL or a pointer to an NV.
The scan stops at the end of the string, or the first invalid character.
Unless C<PERL_SCAN_SILENT_ILLDIGIT> is set in I<*flags>, encountering an
invalid character will also trigger a warning.
On return I<*len> is set to the length of the scanned string,
and I<*flags> gives output flags.

If the value is <= UV_MAX it is returned as a UV, the output flags are clear,
and nothing is written to I<*result>. If the value is > UV_MAX C<grok_hex>
returns UV_MAX, sets C<PERL_SCAN_GREATER_THAN_UV_MAX> in the output flags,
and writes the value to I<*result> (or the value is discarded if I<result>
is NULL).

The hex number may optionally be prefixed with "0x" or "x" unless
C<PERL_SCAN_DISALLOW_PREFIX> is set in I<*flags> on entry. If
C<PERL_SCAN_ALLOW_UNDERSCORES> is set in I<*flags> then the hex
number may use '_' characters to separate digits.

	UV	grok_hex(char* start, STRLEN* len, I32* flags, NV *result)

=for hackers
Found in file numeric.c

=item grok_number

Recognise (or not) a number.  The type of the number is returned
(0 if unrecognised), otherwise it is a bit-ORed combination of
IS_NUMBER_IN_UV, IS_NUMBER_GREATER_THAN_UV_MAX, IS_NUMBER_NOT_INT,
IS_NUMBER_NEG, IS_NUMBER_INFINITY, IS_NUMBER_NAN (defined in perl.h).

If the value of the number can fit an in UV, it is returned in the *valuep
IS_NUMBER_IN_UV will be set to indicate that *valuep is valid, IS_NUMBER_IN_UV
will never be set unless *valuep is valid, but *valuep may have been assigned
to during processing even though IS_NUMBER_IN_UV is not set on return.
If valuep is NULL, IS_NUMBER_IN_UV will be set for the same cases as when
valuep is non-NULL, but no actual assignment (or SEGV) will occur.

IS_NUMBER_NOT_INT will be set with IS_NUMBER_IN_UV if trailing decimals were
seen (in which case *valuep gives the true value truncated to an integer), and
IS_NUMBER_NEG if the number is negative (in which case *valuep holds the
absolute value).  IS_NUMBER_IN_UV is not set if e notation was used or the
number is larger than a UV.

	int	grok_number(const char *pv, STRLEN len, UV *valuep)

=for hackers
Found in file numeric.c

=item grok_numeric_radix

Scan and skip for a numeric decimal separator (radix).

	bool	grok_numeric_radix(const char **sp, const char *send)

=for hackers
Found in file numeric.c

=item grok_oct

converts a string representing an octal number to numeric form.

On entry I<start> and I<*len> give the string to scan, I<*flags> gives
conversion flags, and I<result> should be NULL or a pointer to an NV.
The scan stops at the end of the string, or the first invalid character.
Unless C<PERL_SCAN_SILENT_ILLDIGIT> is set in I<*flags>, encountering an
invalid character will also trigger a warning.
On return I<*len> is set to the length of the scanned string,
and I<*flags> gives output flags.

If the value is <= UV_MAX it is returned as a UV, the output flags are clear,
and nothing is written to I<*result>. If the value is > UV_MAX C<grok_oct>
returns UV_MAX, sets C<PERL_SCAN_GREATER_THAN_UV_MAX> in the output flags,
and writes the value to I<*result> (or the value is discarded if I<result>
is NULL).

If C<PERL_SCAN_ALLOW_UNDERSCORES> is set in I<*flags> then the octal
number may use '_' characters to separate digits.

	UV	grok_oct(char* start, STRLEN* len, I32* flags, NV *result)

=for hackers
Found in file numeric.c

=item scan_bin

For backwards compatibility. Use C<grok_bin> instead.

	NV	scan_bin(char* start, STRLEN len, STRLEN* retlen)

=for hackers
Found in file numeric.c

=item scan_hex

For backwards compatibility. Use C<grok_hex> instead.

	NV	scan_hex(char* start, STRLEN len, STRLEN* retlen)

=for hackers
Found in file numeric.c

=item scan_oct

For backwards compatibility. Use C<grok_oct> instead.

	NV	scan_oct(char* start, STRLEN len, STRLEN* retlen)

=for hackers
Found in file numeric.c


=back

=head1 Optree Manipulation Functions

=over 8

=item cv_const_sv

If C<cv> is a constant sub eligible for inlining. returns the constant
value returned by the sub.  Otherwise, returns NULL.

Constant subs can be created with C<newCONSTSUB> or as described in
L<perlsub/"Constant Functions">.

	SV*	cv_const_sv(CV* cv)

=for hackers
Found in file op.c

=item newCONSTSUB

Creates a constant sub equivalent to Perl C<sub FOO () { 123 }> which is
eligible for inlining at compile-time.

	CV*	newCONSTSUB(HV* stash, char* name, SV* sv)

=for hackers
Found in file op.c

=item newXS

Used by C<xsubpp> to hook up XSUBs as Perl subs.

=for hackers
Found in file op.c


=back

=head1 Pad Data Structures

=over 8

=item pad_sv

Get the value at offset po in the current pad.
Use macro PAD_SV instead of calling this function directly.

	SV*	pad_sv(PADOFFSET po)

=for hackers
Found in file pad.c


=back

=head1 Stack Manipulation Macros

=over 8

=item dMARK

Declare a stack marker variable, C<mark>, for the XSUB.  See C<MARK> and
C<dORIGMARK>.

		dMARK;

=for hackers
Found in file pp.h

=item dORIGMARK

Saves the original stack mark for the XSUB.  See C<ORIGMARK>.

		dORIGMARK;

=for hackers
Found in file pp.h

=item dSP

Declares a local copy of perl's stack pointer for the XSUB, available via
the C<SP> macro.  See C<SP>.

		dSP;

=for hackers
Found in file pp.h

=item EXTEND

Used to extend the argument stack for an XSUB's return values. Once
used, guarantees that there is room for at least C<nitems> to be pushed
onto the stack.

	void	EXTEND(SP, int nitems)

=for hackers
Found in file pp.h

=item MARK

Stack marker variable for the XSUB.  See C<dMARK>.

=for hackers
Found in file pp.h

=item mPUSHi

Push an integer onto the stack.  The stack must have room for this element.
Handles 'set' magic.  Does not use C<TARG>.  See also C<PUSHi>, C<mXPUSHi>
and C<XPUSHi>.

	void	mPUSHi(IV iv)

=for hackers
Found in file pp.h

=item mPUSHn

Push a double onto the stack.  The stack must have room for this element.
Handles 'set' magic.  Does not use C<TARG>.  See also C<PUSHn>, C<mXPUSHn>
and C<XPUSHn>.

	void	mPUSHn(NV nv)

=for hackers
Found in file pp.h

=item mPUSHp

Push a string onto the stack.  The stack must have room for this element.
The C<len> indicates the length of the string.  Handles 'set' magic.  Does
not use C<TARG>.  See also C<PUSHp>, C<mXPUSHp> and C<XPUSHp>.

	void	mPUSHp(char* str, STRLEN len)

=for hackers
Found in file pp.h

=item mPUSHu

Push an unsigned integer onto the stack.  The stack must have room for this
element.  Handles 'set' magic.  Does not use C<TARG>.  See also C<PUSHu>,
C<mXPUSHu> and C<XPUSHu>.

	void	mPUSHu(UV uv)

=for hackers
Found in file pp.h

=item mXPUSHi

Push an integer onto the stack, extending the stack if necessary.  Handles
'set' magic.  Does not use C<TARG>.  See also C<XPUSHi>, C<mPUSHi> and
C<PUSHi>.

	void	mXPUSHi(IV iv)

=for hackers
Found in file pp.h

=item mXPUSHn

Push a double onto the stack, extending the stack if necessary.  Handles
'set' magic.  Does not use C<TARG>.  See also C<XPUSHn>, C<mPUSHn> and
C<PUSHn>.

	void	mXPUSHn(NV nv)

=for hackers
Found in file pp.h

=item mXPUSHp

Push a string onto the stack, extending the stack if necessary.  The C<len>
indicates the length of the string.  Handles 'set' magic.  Does not use
C<TARG>.  See also C<XPUSHp>, C<mPUSHp> and C<PUSHp>.

	void	mXPUSHp(char* str, STRLEN len)

=for hackers
Found in file pp.h

=item mXPUSHu

Push an unsigned integer onto the stack, extending the stack if necessary.
Handles 'set' magic.  Does not use C<TARG>.  See also C<XPUSHu>, C<mPUSHu>
and C<PUSHu>.

	void	mXPUSHu(UV uv)

=for hackers
Found in file pp.h

=item ORIGMARK

The original stack mark for the XSUB.  See C<dORIGMARK>.

=for hackers
Found in file pp.h

=item POPi

Pops an integer off the stack.

	IV	POPi

=for hackers
Found in file pp.h

=item POPl

Pops a long off the stack.

	long	POPl

=for hackers
Found in file pp.h

=item POPn

Pops a double off the stack.

	NV	POPn

=for hackers
Found in file pp.h

=item POPp

Pops a string off the stack. Deprecated. New code should provide
a STRLEN n_a and use POPpx.

	char*	POPp

=for hackers
Found in file pp.h

=item POPpbytex

Pops a string off the stack which must consist of bytes i.e. characters < 256.
Requires a variable STRLEN n_a in scope.

	char*	POPpbytex

=for hackers
Found in file pp.h

=item POPpx

Pops a string off the stack.
Requires a variable STRLEN n_a in scope.

	char*	POPpx

=for hackers
Found in file pp.h

=item POPs

Pops an SV off the stack.

	SV*	POPs

=for hackers
Found in file pp.h

=item PUSHi

Push an integer onto the stack.  The stack must have room for this element.
Handles 'set' magic.  Uses C<TARG>, so C<dTARGET> or C<dXSTARG> should be
called to declare it.  Do not call multiple C<TARG>-oriented macros to 
return lists from XSUB's - see C<mPUSHi> instead.  See also C<XPUSHi> and
C<mXPUSHi>.

	void	PUSHi(IV iv)

=for hackers
Found in file pp.h

=item PUSHMARK

Opening bracket for arguments on a callback.  See C<PUTBACK> and
L<perlcall>.

	void	PUSHMARK(SP)

=for hackers
Found in file pp.h

=item PUSHmortal

Push a new mortal SV onto the stack.  The stack must have room for this
element.  Does not handle 'set' magic.  Does not use C<TARG>.  See also
C<PUSHs>, C<XPUSHmortal> and C<XPUSHs>.

	void	PUSHmortal()

=for hackers
Found in file pp.h

=item PUSHn

Push a double onto the stack.  The stack must have room for this element.
Handles 'set' magic.  Uses C<TARG>, so C<dTARGET> or C<dXSTARG> should be
called to declare it.  Do not call multiple C<TARG>-oriented macros to
return lists from XSUB's - see C<mPUSHn> instead.  See also C<XPUSHn> and
C<mXPUSHn>.

	void	PUSHn(NV nv)

=for hackers
Found in file pp.h

=item PUSHp

Push a string onto the stack.  The stack must have room for this element.
The C<len> indicates the length of the string.  Handles 'set' magic.  Uses
C<TARG>, so C<dTARGET> or C<dXSTARG> should be called to declare it.  Do not
call multiple C<TARG>-oriented macros to return lists from XSUB's - see
C<mPUSHp> instead.  See also C<XPUSHp> and C<mXPUSHp>.

	void	PUSHp(char* str, STRLEN len)

=for hackers
Found in file pp.h

=item PUSHs

Push an SV onto the stack.  The stack must have room for this element.
Does not handle 'set' magic.  Does not use C<TARG>.  See also C<PUSHmortal>,
C<XPUSHs> and C<XPUSHmortal>.

	void	PUSHs(SV* sv)

=for hackers
Found in file pp.h

=item PUSHu

Push an unsigned integer onto the stack.  The stack must have room for this
element.  Handles 'set' magic.  Uses C<TARG>, so C<dTARGET> or C<dXSTARG>
should be called to declare it.  Do not call multiple C<TARG>-oriented
macros to return lists from XSUB's - see C<mPUSHu> instead.  See also
C<XPUSHu> and C<mXPUSHu>.

	void	PUSHu(UV uv)

=for hackers
Found in file pp.h

=item PUTBACK

Closing bracket for XSUB arguments.  This is usually handled by C<xsubpp>.
See C<PUSHMARK> and L<perlcall> for other uses.

		PUTBACK;

=for hackers
Found in file pp.h

=item SP

Stack pointer.  This is usually handled by C<xsubpp>.  See C<dSP> and
C<SPAGAIN>.

=for hackers
Found in file pp.h

=item SPAGAIN

Refetch the stack pointer.  Used after a callback.  See L<perlcall>.

		SPAGAIN;

=for hackers
Found in file pp.h

=item XPUSHi

Push an integer onto the stack, extending the stack if necessary.  Handles
'set' magic.  Uses C<TARG>, so C<dTARGET> or C<dXSTARG> should be called to
declare it.  Do not call multiple C<TARG>-oriented macros to return lists
from XSUB's - see C<mXPUSHi> instead.  See also C<PUSHi> and C<mPUSHi>.

	void	XPUSHi(IV iv)

=for hackers
Found in file pp.h

=item XPUSHmortal

Push a new mortal SV onto the stack, extending the stack if necessary.  Does
not handle 'set' magic.  Does not use C<TARG>.  See also C<XPUSHs>,
C<PUSHmortal> and C<PUSHs>.

	void	XPUSHmortal()

=for hackers
Found in file pp.h

=item XPUSHn

Push a double onto the stack, extending the stack if necessary.  Handles
'set' magic.  Uses C<TARG>, so C<dTARGET> or C<dXSTARG> should be called to
declare it.  Do not call multiple C<TARG>-oriented macros to return lists
from XSUB's - see C<mXPUSHn> instead.  See also C<PUSHn> and C<mPUSHn>.

	void	XPUSHn(NV nv)

=for hackers
Found in file pp.h

=item XPUSHp

Push a string onto the stack, extending the stack if necessary.  The C<len>
indicates the length of the string.  Handles 'set' magic.  Uses C<TARG>, so
C<dTARGET> or C<dXSTARG> should be called to declare it.  Do not call
multiple C<TARG>-oriented macros to return lists from XSUB's - see
C<mXPUSHp> instead.  See also C<PUSHp> and C<mPUSHp>.

	void	XPUSHp(char* str, STRLEN len)

=for hackers
Found in file pp.h

=item XPUSHs

Push an SV onto the stack, extending the stack if necessary.  Does not
handle 'set' magic.  Does not use C<TARG>.  See also C<XPUSHmortal>,
C<PUSHs> and C<PUSHmortal>.

	void	XPUSHs(SV* sv)

=for hackers
Found in file pp.h

=item XPUSHu

Push an unsigned integer onto the stack, extending the stack if necessary.
Handles 'set' magic.  Uses C<TARG>, so C<dTARGET> or C<dXSTARG> should be
called to declare it.  Do not call multiple C<TARG>-oriented macros to
return lists from XSUB's - see C<mXPUSHu> instead.  See also C<PUSHu> and
C<mPUSHu>.

	void	XPUSHu(UV uv)

=for hackers
Found in file pp.h

=item XSRETURN

Return from XSUB, indicating number of items on the stack.  This is usually
handled by C<xsubpp>.

	void	XSRETURN(int nitems)

=for hackers
Found in file XSUB.h

=item XSRETURN_EMPTY

Return an empty list from an XSUB immediately.

		XSRETURN_EMPTY;

=for hackers
Found in file XSUB.h

=item XSRETURN_IV

Return an integer from an XSUB immediately.  Uses C<XST_mIV>.

	void	XSRETURN_IV(IV iv)

=for hackers
Found in file XSUB.h

=item XSRETURN_NO

Return C<&PL_sv_no> from an XSUB immediately.  Uses C<XST_mNO>.

		XSRETURN_NO;

=for hackers
Found in file XSUB.h

=item XSRETURN_NV

Return a double from an XSUB immediately.  Uses C<XST_mNV>.

	void	XSRETURN_NV(NV nv)

=for hackers
Found in file XSUB.h

=item XSRETURN_PV

Return a copy of a string from an XSUB immediately.  Uses C<XST_mPV>.

	void	XSRETURN_PV(char* str)

=for hackers
Found in file XSUB.h

=item XSRETURN_UNDEF

Return C<&PL_sv_undef> from an XSUB immediately.  Uses C<XST_mUNDEF>.

		XSRETURN_UNDEF;

=for hackers
Found in file XSUB.h

=item XSRETURN_UV

Return an integer from an XSUB immediately.  Uses C<XST_mUV>.

	void	XSRETURN_UV(IV uv)

=for hackers
Found in file XSUB.h

=item XSRETURN_YES

Return C<&PL_sv_yes> from an XSUB immediately.  Uses C<XST_mYES>.

		XSRETURN_YES;

=for hackers
Found in file XSUB.h

=item XST_mIV

Place an integer into the specified position C<pos> on the stack.  The
value is stored in a new mortal SV.

	void	XST_mIV(int pos, IV iv)

=for hackers
Found in file XSUB.h

=item XST_mNO

Place C<&PL_sv_no> into the specified position C<pos> on the
stack.

	void	XST_mNO(int pos)

=for hackers
Found in file XSUB.h

=item XST_mNV

Place a double into the specified position C<pos> on the stack.  The value
is stored in a new mortal SV.

	void	XST_mNV(int pos, NV nv)

=for hackers
Found in file XSUB.h

=item XST_mPV

Place a copy of a string into the specified position C<pos> on the stack. 
The value is stored in a new mortal SV.

	void	XST_mPV(int pos, char* str)

=for hackers
Found in file XSUB.h

=item XST_mUNDEF

Place C<&PL_sv_undef> into the specified position C<pos> on the
stack.

	void	XST_mUNDEF(int pos)

=for hackers
Found in file XSUB.h

=item XST_mYES

Place C<&PL_sv_yes> into the specified position C<pos> on the
stack.

	void	XST_mYES(int pos)

=for hackers
Found in file XSUB.h


=back

=head1 SV Flags

=over 8

=item svtype

An enum of flags for Perl types.  These are found in the file B<sv.h>
in the C<svtype> enum.  Test these flags with the C<SvTYPE> macro.

=for hackers
Found in file sv.h

=item SVt_IV

Integer type flag for scalars.  See C<svtype>.

=for hackers
Found in file sv.h

=item SVt_NV

Double type flag for scalars.  See C<svtype>.

=for hackers
Found in file sv.h

=item SVt_PV

Pointer type flag for scalars.  See C<svtype>.

=for hackers
Found in file sv.h

=item SVt_PVAV

Type flag for arrays.  See C<svtype>.

=for hackers
Found in file sv.h

=item SVt_PVCV

Type flag for code refs.  See C<svtype>.

=for hackers
Found in file sv.h

=item SVt_PVHV

Type flag for hashes.  See C<svtype>.

=for hackers
Found in file sv.h

=item SVt_PVMG

Type flag for blessed scalars.  See C<svtype>.

=for hackers
Found in file sv.h


=back

=head1 SV Manipulation Functions

=over 8

=item get_sv

Returns the SV of the specified Perl scalar.  If C<create> is set and the
Perl variable does not exist then it will be created.  If C<create> is not
set and the variable does not exist then NULL is returned.

NOTE: the perl_ form of this function is deprecated.

	SV*	get_sv(const char* name, I32 create)

=for hackers
Found in file perl.c

=item looks_like_number

Test if the content of an SV looks like a number (or is a number).
C<Inf> and C<Infinity> are treated as numbers (so will not issue a
non-numeric warning), even if your atof() doesn't grok them.

	I32	looks_like_number(SV* sv)

=for hackers
Found in file sv.c

=item newRV_inc

Creates an RV wrapper for an SV.  The reference count for the original SV is
incremented.

	SV*	newRV_inc(SV* sv)

=for hackers
Found in file sv.h

=item newRV_noinc

Creates an RV wrapper for an SV.  The reference count for the original
SV is B<not> incremented.

	SV*	newRV_noinc(SV *sv)

=for hackers
Found in file sv.c

=item NEWSV

Creates a new SV.  A non-zero C<len> parameter indicates the number of
bytes of preallocated string space the SV should have.  An extra byte for a
tailing NUL is also reserved.  (SvPOK is not set for the SV even if string
space is allocated.)  The reference count for the new SV is set to 1.
C<id> is an integer id between 0 and 1299 (used to identify leaks).

	SV*	NEWSV(int id, STRLEN len)

=for hackers
Found in file handy.h

=item newSV

Create a new null SV, or if len > 0, create a new empty SVt_PV type SV
with an initial PV allocation of len+1. Normally accessed via the C<NEWSV>
macro.

	SV*	newSV(STRLEN len)

=for hackers
Found in file sv.c

=item newSViv

Creates a new SV and copies an integer into it.  The reference count for the
SV is set to 1.

	SV*	newSViv(IV i)

=for hackers
Found in file sv.c

=item newSVnv

Creates a new SV and copies a floating point value into it.
The reference count for the SV is set to 1.

	SV*	newSVnv(NV n)

=for hackers
Found in file sv.c

=item newSVpv

Creates a new SV and copies a string into it.  The reference count for the
SV is set to 1.  If C<len> is zero, Perl will compute the length using
strlen().  For efficiency, consider using C<newSVpvn> instead.

	SV*	newSVpv(const char* s, STRLEN len)

=for hackers
Found in file sv.c

=item newSVpvf

Creates a new SV and initializes it with the string formatted like
C<sprintf>.

	SV*	newSVpvf(const char* pat, ...)

=for hackers
Found in file sv.c

=item newSVpvn

Creates a new SV and copies a string into it.  The reference count for the
SV is set to 1.  Note that if C<len> is zero, Perl will create a zero length
string.  You are responsible for ensuring that the source string is at least
C<len> bytes long.  If the C<s> argument is NULL the new SV will be undefined.

	SV*	newSVpvn(const char* s, STRLEN len)

=for hackers
Found in file sv.c

=item newSVpvn_share

Creates a new SV with its SvPVX pointing to a shared string in the string
table. If the string does not already exist in the table, it is created
first.  Turns on READONLY and FAKE.  The string's hash is stored in the UV
slot of the SV; if the C<hash> parameter is non-zero, that value is used;
otherwise the hash is computed.  The idea here is that as the string table
is used for shared hash keys these strings will have SvPVX == HeKEY and
hash lookup will avoid string compare.

	SV*	newSVpvn_share(const char* s, I32 len, U32 hash)

=for hackers
Found in file sv.c

=item newSVrv

Creates a new SV for the RV, C<rv>, to point to.  If C<rv> is not an RV then
it will be upgraded to one.  If C<classname> is non-null then the new SV will
be blessed in the specified package.  The new SV is returned and its
reference count is 1.

	SV*	newSVrv(SV* rv, const char* classname)

=for hackers
Found in file sv.c

=item newSVsv

Creates a new SV which is an exact duplicate of the original SV.
(Uses C<sv_setsv>).

	SV*	newSVsv(SV* old)

=for hackers
Found in file sv.c

=item newSVuv

Creates a new SV and copies an unsigned integer into it.
The reference count for the SV is set to 1.

	SV*	newSVuv(UV u)

=for hackers
Found in file sv.c

=item SvCUR

Returns the length of the string which is in the SV.  See C<SvLEN>.

	STRLEN	SvCUR(SV* sv)

=for hackers
Found in file sv.h

=item SvCUR_set

Set the length of the string which is in the SV.  See C<SvCUR>.

	void	SvCUR_set(SV* sv, STRLEN len)

=for hackers
Found in file sv.h

=item SvEND

Returns a pointer to the last character in the string which is in the SV.
See C<SvCUR>.  Access the character as *(SvEND(sv)).

	char*	SvEND(SV* sv)

=for hackers
Found in file sv.h

=item SvGROW

Expands the character buffer in the SV so that it has room for the
indicated number of bytes (remember to reserve space for an extra trailing
NUL character).  Calls C<sv_grow> to perform the expansion if necessary.
Returns a pointer to the character buffer.

	char *	SvGROW(SV* sv, STRLEN len)

=for hackers
Found in file sv.h

=item SvIOK

Returns a boolean indicating whether the SV contains an integer.

	bool	SvIOK(SV* sv)

=for hackers
Found in file sv.h

=item SvIOKp

Returns a boolean indicating whether the SV contains an integer.  Checks
the B<private> setting.  Use C<SvIOK>.

	bool	SvIOKp(SV* sv)

=for hackers
Found in file sv.h

=item SvIOK_notUV

Returns a boolean indicating whether the SV contains a signed integer.

	bool	SvIOK_notUV(SV* sv)

=for hackers
Found in file sv.h

=item SvIOK_off

Unsets the IV status of an SV.

	void	SvIOK_off(SV* sv)

=for hackers
Found in file sv.h

=item SvIOK_on

Tells an SV that it is an integer.

	void	SvIOK_on(SV* sv)

=for hackers
Found in file sv.h

=item SvIOK_only

Tells an SV that it is an integer and disables all other OK bits.

	void	SvIOK_only(SV* sv)

=for hackers
Found in file sv.h

=item SvIOK_only_UV

Tells and SV that it is an unsigned integer and disables all other OK bits.

	void	SvIOK_only_UV(SV* sv)

=for hackers
Found in file sv.h

=item SvIOK_UV

Returns a boolean indicating whether the SV contains an unsigned integer.

	bool	SvIOK_UV(SV* sv)

=for hackers
Found in file sv.h

=item SvIsCOW

Returns a boolean indicating whether the SV is Copy-On-Write. (either shared
hash key scalars, or full Copy On Write scalars if 5.9.0 is configured for
COW)

	bool	SvIsCOW(SV* sv)

=for hackers
Found in file sv.h

=item SvIsCOW_shared_hash

Returns a boolean indicating whether the SV is Copy-On-Write shared hash key
scalar.

	bool	SvIsCOW_shared_hash(SV* sv)

=for hackers
Found in file sv.h

=item SvIV

Coerces the given SV to an integer and returns it. See  C<SvIVx> for a
version which guarantees to evaluate sv only once.

	IV	SvIV(SV* sv)

=for hackers
Found in file sv.h

=item SvIVx

Coerces the given SV to an integer and returns it. Guarantees to evaluate
sv only once. Use the more efficient C<SvIV> otherwise.

	IV	SvIVx(SV* sv)

=for hackers
Found in file sv.h

=item SvIVX

Returns the raw value in the SV's IV slot, without checks or conversions.
Only use when you are sure SvIOK is true. See also C<SvIV()>.

	IV	SvIVX(SV* sv)

=for hackers
Found in file sv.h

=item SvIV_nomg

Like C<SvIV> but doesn't process magic.

	IV	SvIV_nomg(SV* sv)

=for hackers
Found in file sv.h

=item SvLEN

Returns the size of the string buffer in the SV, not including any part
attributable to C<SvOOK>.  See C<SvCUR>.

	STRLEN	SvLEN(SV* sv)

=for hackers
Found in file sv.h

=item SvNIOK

Returns a boolean indicating whether the SV contains a number, integer or
double.

	bool	SvNIOK(SV* sv)

=for hackers
Found in file sv.h

=item SvNIOKp

Returns a boolean indicating whether the SV contains a number, integer or
double.  Checks the B<private> setting.  Use C<SvNIOK>.

	bool	SvNIOKp(SV* sv)

=for hackers
Found in file sv.h

=item SvNIOK_off

Unsets the NV/IV status of an SV.

	void	SvNIOK_off(SV* sv)

=for hackers
Found in file sv.h

=item SvNOK

Returns a boolean indicating whether the SV contains a double.

	bool	SvNOK(SV* sv)

=for hackers
Found in file sv.h

=item SvNOKp

Returns a boolean indicating whether the SV contains a double.  Checks the
B<private> setting.  Use C<SvNOK>.

	bool	SvNOKp(SV* sv)

=for hackers
Found in file sv.h

=item SvNOK_off

Unsets the NV status of an SV.

	void	SvNOK_off(SV* sv)

=for hackers
Found in file sv.h

=item SvNOK_on

Tells an SV that it is a double.

	void	SvNOK_on(SV* sv)

=for hackers
Found in file sv.h

=item SvNOK_only

Tells an SV that it is a double and disables all other OK bits.

	void	SvNOK_only(SV* sv)

=for hackers
Found in file sv.h

=item SvNV

Coerce the given SV to a double and return it. See  C<SvNVx> for a version
which guarantees to evaluate sv only once.

	NV	SvNV(SV* sv)

=for hackers
Found in file sv.h

=item SvNVX

Returns the raw value in the SV's NV slot, without checks or conversions.
Only use when you are sure SvNOK is true. See also C<SvNV()>.

	NV	SvNVX(SV* sv)

=for hackers
Found in file sv.h

=item SvNVx

Coerces the given SV to a double and returns it. Guarantees to evaluate
sv only once. Use the more efficient C<SvNV> otherwise.

	NV	SvNVx(SV* sv)

=for hackers
Found in file sv.h

=item SvOK

Returns a boolean indicating whether the value is an SV. It also tells
whether the value is defined or not.

	bool	SvOK(SV* sv)

=for hackers
Found in file sv.h

=item SvOOK

Returns a boolean indicating whether the SvIVX is a valid offset value for
the SvPVX.  This hack is used internally to speed up removal of characters
from the beginning of a SvPV.  When SvOOK is true, then the start of the
allocated string buffer is really (SvPVX - SvIVX).

	bool	SvOOK(SV* sv)

=for hackers
Found in file sv.h

=item SvPOK

Returns a boolean indicating whether the SV contains a character
string.

	bool	SvPOK(SV* sv)

=for hackers
Found in file sv.h

=item SvPOKp

Returns a boolean indicating whether the SV contains a character string.
Checks the B<private> setting.  Use C<SvPOK>.

	bool	SvPOKp(SV* sv)

=for hackers
Found in file sv.h

=item SvPOK_off

Unsets the PV status of an SV.

	void	SvPOK_off(SV* sv)

=for hackers
Found in file sv.h

=item SvPOK_on

Tells an SV that it is a string.

	void	SvPOK_on(SV* sv)

=for hackers
Found in file sv.h

=item SvPOK_only

Tells an SV that it is a string and disables all other OK bits.
Will also turn off the UTF-8 status.

	void	SvPOK_only(SV* sv)

=for hackers
Found in file sv.h

=item SvPOK_only_UTF8

Tells an SV that it is a string and disables all other OK bits,
and leaves the UTF-8 status as it was.

	void	SvPOK_only_UTF8(SV* sv)

=for hackers
Found in file sv.h

=item SvPV

Returns a pointer to the string in the SV, or a stringified form of
the SV if the SV does not contain a string.  The SV may cache the
stringified version becoming C<SvPOK>.  Handles 'get' magic. See also
C<SvPVx> for a version which guarantees to evaluate sv only once.

	char*	SvPV(SV* sv, STRLEN len)

=for hackers
Found in file sv.h

=item SvPVbyte

Like C<SvPV>, but converts sv to byte representation first if necessary.

	char*	SvPVbyte(SV* sv, STRLEN len)

=for hackers
Found in file sv.h

=item SvPVbytex

Like C<SvPV>, but converts sv to byte representation first if necessary.
Guarantees to evaluate sv only once; use the more efficient C<SvPVbyte>
otherwise.

	char*	SvPVbytex(SV* sv, STRLEN len)

=for hackers
Found in file sv.h

=item SvPVbytex_force

Like C<SvPV_force>, but converts sv to byte representation first if necessary.
Guarantees to evaluate sv only once; use the more efficient C<SvPVbyte_force>
otherwise.

	char*	SvPVbytex_force(SV* sv, STRLEN len)

=for hackers
Found in file sv.h

=item SvPVbyte_force

Like C<SvPV_force>, but converts sv to byte representation first if necessary.

	char*	SvPVbyte_force(SV* sv, STRLEN len)

=for hackers
Found in file sv.h

=item SvPVbyte_nolen

Like C<SvPV_nolen>, but converts sv to byte representation first if necessary.

	char*	SvPVbyte_nolen(SV* sv)

=for hackers
Found in file sv.h

=item SvPVutf8

Like C<SvPV>, but converts sv to utf8 first if necessary.

	char*	SvPVutf8(SV* sv, STRLEN len)

=for hackers
Found in file sv.h

=item SvPVutf8x

Like C<SvPV>, but converts sv to utf8 first if necessary.
Guarantees to evaluate sv only once; use the more efficient C<SvPVutf8>
otherwise.

	char*	SvPVutf8x(SV* sv, STRLEN len)

=for hackers
Found in file sv.h

=item SvPVutf8x_force

Like C<SvPV_force>, but converts sv to utf8 first if necessary.
Guarantees to evaluate sv only once; use the more efficient C<SvPVutf8_force>
otherwise.

	char*	SvPVutf8x_force(SV* sv, STRLEN len)

=for hackers
Found in file sv.h

=item SvPVutf8_force

Like C<SvPV_force>, but converts sv to utf8 first if necessary.

	char*	SvPVutf8_force(SV* sv, STRLEN len)

=for hackers
Found in file sv.h

=item SvPVutf8_nolen

Like C<SvPV_nolen>, but converts sv to utf8 first if necessary.

	char*	SvPVutf8_nolen(SV* sv)

=for hackers
Found in file sv.h

=item SvPVx

A version of C<SvPV> which guarantees to evaluate sv only once.

	char*	SvPVx(SV* sv, STRLEN len)

=for hackers
Found in file sv.h

=item SvPVX

Returns a pointer to the physical string in the SV.  The SV must contain a
string.

	char*	SvPVX(SV* sv)

=for hackers
Found in file sv.h

=item SvPV_force

Like C<SvPV> but will force the SV into containing just a string
(C<SvPOK_only>).  You want force if you are going to update the C<SvPVX>
directly.

	char*	SvPV_force(SV* sv, STRLEN len)

=for hackers
Found in file sv.h

=item SvPV_force_nomg

Like C<SvPV> but will force the SV into containing just a string
(C<SvPOK_only>).  You want force if you are going to update the C<SvPVX>
directly. Doesn't process magic.

	char*	SvPV_force_nomg(SV* sv, STRLEN len)

=for hackers
Found in file sv.h

=item SvPV_nolen