Manual:

Reference:

Contact:

Site maintained by
Jon Allen (JJ)
Last updated on
23 April 2006
See the project page for more details

Show navigation

-- Perl 5.8.8 documentation --

Show toolbar

perlapi

NAME
DESCRIPTION
"Gimme" Values
Array Manipulation Functions
Callback Functions
Character classes
Cloning an interpreter
CV Manipulation Functions
Embedding Functions
Functions in file pp_pack.c
Global Variables
GV Functions
Handy Values
Hash Manipulation Functions
Magical Functions
Memory Management
Miscellaneous Functions
Numeric functions
Optree Manipulation Functions
Pad Data Structures
Stack Manipulation Macros
SV Flags
SV Manipulation Functions
Unicode Support
Variables created by xsubpp and xsubpp internal functions
Warning and Dieing
AUTHORS
SEE ALSO

NAME

perlapi - autogenerated documentation for the perl public API

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 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.

"Gimme" Values

GIMME
A backward-compatible version of GIMME_V which can only return G_SCALAR or G_ARRAY ; in a void context, it returns G_SCALAR . Deprecated. Use GIMME_V instead.
```
	U32	GIMME
```
GIMME_V
The XSUB-writer's equivalent to Perl's wantarray. Returns G_VOID , G_SCALAR or G_ARRAY for void, scalar or list context, respectively.
```
	U32	GIMME_V
```
G_ARRAY
Used to indicate list context. See GIMME_V , GIMME and perlcall.
G_DISCARD
Indicates that arguments returned from a callback should be discarded. See perlcall.
G_EVAL
Used to force a Perl eval wrapper around a callback. See perlcall.
G_NOARGS
Indicates that no arguments are being sent to a callback. See perlcall.
G_SCALAR
Used to indicate scalar context. See GIMME_V , GIMME , and perlcall.
G_VOID
Used to indicate void context. See GIMME_V and perlcall.

Array Manipulation Functions

AvFILL
Same as av_len() . Deprecated, use av_len() instead.
```
	int	AvFILL(AV* av)
```
av_clear
Clears an array, making it empty. Does not free the memory used by the array itself.
```
	void	av_clear(AV* ar)
```
av_delete
Deletes the element indexed by key from the array. Returns the deleted element. If flags equals G_DISCARD , the element is freed and null is returned.
```
	SV*	av_delete(AV* ar, I32 key, I32 flags)
```
av_exists
Returns true if the element indexed by key has been initialized.

This relies on the fact that uninitialized array elements are set to &PL_sv_undef .
```
	bool	av_exists(AV* ar, I32 key)
```
av_extend
Pre-extend an array. The key is the index to which the array should be extended.
```
	void	av_extend(AV* ar, I32 key)
```
av_fetch
Returns the SV at the specified index in the array. The key is the index. If 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 SV* .

See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied arrays.
```
	SV**	av_fetch(AV* ar, I32 key, I32 lval)
```
av_fill
Ensure than an array has a given number of elements, equivalent to Perl's $#array = $fill; .
```
	void	av_fill(AV* ar, I32 fill)
```
av_len
Returns the highest index in the array. Returns -1 if the array is empty.
```
	I32	av_len(AV* ar)
```
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)
```
av_pop
Pops an SV off the end of the array. Returns &PL_sv_undef if the array is empty.
```
	SV*	av_pop(AV* ar)
```
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)
```
av_shift
Shifts an SV off the beginning of the array.
```
	SV*	av_shift(AV* ar)
```
av_store
Stores an SV in an array. The array index is specified as 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 SV* . Note that the caller is responsible for suitably incrementing the reference count of val before the call, and decrementing it if the function returned NULL.

See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied arrays.
```
	SV**	av_store(AV* ar, I32 key, SV* val)
```
av_undef
Undefines the array. Frees the memory used by the array itself.
```
	void	av_undef(AV* ar)
```
av_unshift
Unshift the given number of undef values onto the beginning of the array. The array will grow automatically to accommodate the addition. You must then use av_store to assign values to these new elements.
```
	void	av_unshift(AV* ar, I32 num)
```
get_av
Returns the AV of the specified Perl array. If create is set and the Perl variable does not exist then it will be created. If 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)
```
newAV
Creates a new AV. The reference count is set to 1.
```
	AV*	newAV()
```

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)

Callback Functions

call_argv
Performs a callback to the specified Perl sub. See perlcall.

NOTE: the perl_ form of this function is deprecated.
```
	I32	call_argv(const char* sub_name, I32 flags, char** argv)
```
call_method
Performs a callback to the specified Perl method. The blessed object must be on the stack. See perlcall.

NOTE: the perl_ form of this function is deprecated.
```
	I32	call_method(const char* methname, I32 flags)
```
call_pv
Performs a callback to the specified Perl sub. See perlcall.

NOTE: the perl_ form of this function is deprecated.
```
	I32	call_pv(const char* sub_name, I32 flags)
```
call_sv
Performs a callback to the Perl sub whose name is in the SV. See perlcall.

NOTE: the perl_ form of this function is deprecated.
```
	I32	call_sv(SV* sv, I32 flags)
```
ENTER
Opening bracket on a callback. See LEAVE and perlcall.
```
		ENTER;
```
eval_pv
Tells Perl to 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)
```
eval_sv
Tells Perl to eval the string in the SV.

NOTE: the perl_ form of this function is deprecated.
```
	I32	eval_sv(SV* sv, I32 flags)
```
FREETMPS
Closing bracket for temporaries on a callback. See SAVETMPS and perlcall.
```
		FREETMPS;
```
LEAVE
Closing bracket on a callback. See ENTER and perlcall.
```
		LEAVE;
```
SAVETMPS
Opening bracket for temporaries on a callback. See FREETMPS and perlcall.
```
		SAVETMPS;
```

Character classes

isALNUM
Returns a boolean indicating whether the C char is an ASCII alphanumeric character (including underscore) or digit.
```
	bool	isALNUM(char ch)
```
isALPHA
Returns a boolean indicating whether the C char is an ASCII alphabetic character.
```
	bool	isALPHA(char ch)
```
isDIGIT
Returns a boolean indicating whether the C char is an ASCII digit.
```
	bool	isDIGIT(char ch)
```
isLOWER
Returns a boolean indicating whether the C char is a lowercase character.
```
	bool	isLOWER(char ch)
```
isSPACE
Returns a boolean indicating whether the C char is whitespace.
```
	bool	isSPACE(char ch)
```
isUPPER
Returns a boolean indicating whether the C char is an uppercase character.
```
	bool	isUPPER(char ch)
```
toLOWER
Converts the specified character to lowercase.
```
	char	toLOWER(char ch)
```
toUPPER
Converts the specified character to uppercase.
```
	char	toUPPER(char ch)
```

Cloning an interpreter

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 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)
```

CV Manipulation Functions

CvSTASH
Returns the stash of the CV.
```
	HV*	CvSTASH(CV* cv)
```
get_cv
Returns the CV of the specified Perl subroutine. If create is set and the Perl subroutine does not exist then it will be declared (which has the same effect as saying sub name; ). If 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)
```

Embedding Functions

cv_undef
Clear out all the active components of a CV. This can happen either by an explicit 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)
```
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 use Foo::Bar VERSION . The optional trailing SV* arguments can be used to specify arguments to the module's import() method, similar to use Foo::Bar VERSION LIST .
```
	void	load_module(U32 flags, SV* name, SV* ver, ...)
```
nothreadhook
Stub that provides thread hook for perl_destruct when there are no threads.
```
	int	nothreadhook()
```
perl_alloc
Allocates a new Perl interpreter. See perlembed.
```
	PerlInterpreter*	perl_alloc()
```
perl_construct
Initializes a new Perl interpreter. See perlembed.
```
	void	perl_construct(PerlInterpreter* interp)
```
perl_destruct
Shuts down a Perl interpreter. See perlembed.
```
	int	perl_destruct(PerlInterpreter* interp)
```
perl_free
Releases a Perl interpreter. See perlembed.
```
	void	perl_free(PerlInterpreter* interp)
```

perl_parse

Tells a Perl interpreter to parse a Perl script. See perlembed.

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

perl_run
Tells a Perl interpreter to run. See perlembed.
```
	int	perl_run(PerlInterpreter* interp)
```
require_pv
Tells Perl to require the file named by the string argument. It is analogous to the Perl code 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)
```

Functions in file pp_pack.c

packlist

The engine implementing pack() Perl function.

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

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)
```
unpackstring
The engine implementing unpack() Perl function. unpackstring puts the extracted list items on the stack and returns the number of elements. Issue PUTBACK before and SPAGAIN after the call to this function.
```
	I32	unpackstring(char *pat, char *patend, char *s, char *strend, U32 flags)
```
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)
```

Global Variables

PL_modglobal
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
```
PL_na
A convenience variable which is typically used with 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 SvPV_nolen macro.
```
	STRLEN	PL_na
```
PL_sv_no
This is the false SV. See PL_sv_yes . Always refer to this as &PL_sv_no .
```
	SV	PL_sv_no
```
PL_sv_undef
This is the undef SV. Always refer to this as &PL_sv_undef .
```
	SV	PL_sv_undef
```
PL_sv_yes
This is the true SV. See PL_sv_no . Always refer to this as &PL_sv_yes .
```
	SV	PL_sv_yes
```

GV Functions

GvSV
Return the SV from the GV.
```
	SV*	GvSV(GV* gv)
```
gv_fetchmeth
Returns the glob with the given name and a defined subroutine or NULL . The glob lives in the given stash , or in the stashes accessible via @ISA and UNIVERSAL::.

The argument level should be either 0 or -1. If level==0 , as a side-effect creates a glob with the given name in the given 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 "SUPER" token as a postfix of the stash name. The GV returned from gv_fetchmeth may be a method cache entry, which is not visible to Perl code. So when calling 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 GvCV macro.
```
	GV*	gv_fetchmeth(HV* stash, const char* name, STRLEN len, I32 level)
```

gv_fetchmethod

See gv_fetchmethod_autoload.

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

gv_fetchmethod_autoload
Returns the glob which contains the subroutine to call to invoke the method on the 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 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 gv_fetchmethod is equivalent to calling gv_fetchmethod_autoload with a non-zero autoload parameter.

These functions grant "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 gv_fetchmeth with level==0 . name should be writable if contains ':' or ' ''. The warning against passing the GV returned by gv_fetchmeth to call_sv apply equally to these functions.
```
	GV*	gv_fetchmethod_autoload(HV* stash, const char* name, I32 autoload)
```
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 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)
```
gv_stashpv
Returns a pointer to the stash for a specified package. name should be a valid UTF-8 string and must be null-terminated. If create is set then the package will be created if it does not already exist. If create is not set and the package does not exist then NULL is returned.
```
	HV*	gv_stashpv(const char* name, I32 create)
```
gv_stashpvn
Returns a pointer to the stash for a specified package. name should be a valid UTF-8 string. The namelen parameter indicates the length of the name , in bytes. If create is set then the package will be created if it does not already exist. If create is not set and the package does not exist then NULL is returned.
```
	HV*	gv_stashpvn(const char* name, U32 namelen, I32 create)
```
gv_stashsv
Returns a pointer to the stash for a specified package, which must be a valid UTF-8 string. See gv_stashpv .
```
	HV*	gv_stashsv(SV* sv, I32 create)
```

Handy Values

Nullav
Null AV pointer.
Nullch
Null character pointer.
Nullcv
Null CV pointer.
Nullhv
Null HV pointer.
Nullsv
Null SV pointer.

Hash Manipulation Functions

get_hv
Returns the HV of the specified Perl hash. If create is set and the Perl variable does not exist then it will be created. If 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)
```
HEf_SVKEY
This flag, used in the length slot of hash entries and magic structures, specifies the structure contains an SV* pointer where a char* pointer is to be expected. (For information only--not to be used).
HeHASH
Returns the computed hash stored in the hash entry.
```
	U32	HeHASH(HE* he)
```
HeKEY
Returns the actual pointer stored in the key slot of the hash entry. The pointer may be either char* or SV* , depending on the value of HeKLEN() . Can be assigned to. The HePV() or HeSVKEY() macros are usually preferable for finding the value of a key.
```
	void*	HeKEY(HE* he)
```
HeKLEN
If this is negative, and amounts to HEf_SVKEY , it indicates the entry holds an SV* key. Otherwise, holds the actual length of the key. Can be assigned to. The HePV() macro is usually preferable for finding key lengths.
```
	STRLEN	HeKLEN(HE* he)
```
HePV
Returns the key slot of the hash entry as a char* value, doing any necessary dereferencing of possibly SV* keys. The length of the string is placed in len (this is a macro, so do not use &len ). If you do not care about what the length of the key is, you may use the global variable 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 strlen() or similar is not a good way to find the length of hash keys. This is very similar to the SvPV() macro described elsewhere in this document.
```
	char*	HePV(HE* he, STRLEN len)
```
HeSVKEY
Returns the key as an SV* , or Nullsv if the hash entry does not contain an SV* key.
```
	SV*	HeSVKEY(HE* he)
```
HeSVKEY_force
Returns the key as an SV* . Will create and return a temporary mortal SV* if the hash entry contains only a char* key.
```
	SV*	HeSVKEY_force(HE* he)
```
HeSVKEY_set
Sets the key to a given SV* , taking care to set the appropriate flags to indicate the presence of an SV* key, and returns the same SV* .
```
	SV*	HeSVKEY_set(HE* he, SV* sv)
```
HeVAL
Returns the value slot (type SV* ) stored in the hash entry.
```
	SV*	HeVAL(HE* he)
```
HvNAME
Returns the package name of a stash. See SvSTASH , CvSTASH .
```
	char*	HvNAME(HV* stash)
```
hv_clear
Clears a hash, making it empty.
```
	void	hv_clear(HV* tb)
```
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)
```
hv_delete
Deletes a key/value pair in the hash. The value SV is removed from the hash and returned to the caller. The klen is the length of the key. The 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)
```
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 flags value will normally be zero; if set to G_DISCARD then NULL will be returned. 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)
```
hv_exists
Returns a boolean indicating whether the specified hash key exists. The klen is the length of the key.
```
	bool	hv_exists(HV* tb, const char* key, I32 klen)
```
hv_exists_ent
Returns a boolean indicating whether the specified hash key exists. 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)
```
hv_fetch
Returns the SV which corresponds to the specified key in the hash. The klen is the length of the key. If 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 SV* .

See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied hashes.
```
	SV**	hv_fetch(HV* tb, const char* key, I32 klen, I32 lval)
```
hv_fetch_ent
Returns the hash entry which corresponds to the specified key in the hash. hash must be a valid precomputed hash number for the given key , or 0 if you want the function to compute it. IF 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 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 "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied hashes.
```
	HE*	hv_fetch_ent(HV* tb, SV* key, I32 lval, U32 hash)
```
hv_iterinit
Prepares a starting point to traverse a hash table. Returns the number of keys in the hash (i.e. the same as HvKEYS(tb) ). The return value is currently only meaningful for hashes without tie magic.

NOTE: Before version 5.004_65, 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 HvFILL(tb) .
```
	I32	hv_iterinit(HV* tb)
```
hv_iterkey
Returns the key from the current position of the hash iterator. See hv_iterinit .
```
	char*	hv_iterkey(HE* entry, I32* retlen)
```
hv_iterkeysv
Returns the key as an SV* from the current position of the hash iterator. The return value will always be a mortal copy of the key. Also see hv_iterinit .
```
	SV*	hv_iterkeysv(HE* entry)
```
hv_iternext
Returns entries from a hash iterator. See hv_iterinit .

You may call hv_delete or 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 hv_iternext , so you must not discard your iterator immediately else the entry will leak - call hv_iternext to trigger the resource deallocation.
```
	HE*	hv_iternext(HV* tb)
```
hv_iternextsv
Performs an hv_iternext , hv_iterkey , and hv_iterval in one operation.
```
	SV*	hv_iternextsv(HV* hv, char** key, I32* retlen)
```
hv_iternext_flags
Returns entries from a hash iterator. See hv_iterinit and hv_iternext . The 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 &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)
```
hv_iterval
Returns the value from the current position of the hash iterator. See hv_iterkey .
```
	SV*	hv_iterval(HV* tb, HE* entry)
```
hv_magic
Adds magic to a hash. See sv_magic .
```
	void	hv_magic(HV* hv, GV* gv, int how)
```
hv_scalar
Evaluates the hash in scalar context and returns the result. Handles magic when the hash is tied.
```
	SV*	hv_scalar(HV* hv)
```
hv_store
Stores an SV in a hash. The hash key is specified as key and klen is the length of the key. The 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 SV* . Note that the caller is responsible for suitably incrementing the reference count of val before the call, and decrementing it if the function returned NULL. Effectively a successful hv_store takes ownership of one reference to 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 "Understanding the Magic of Tied Hashes and Arrays" in perlguts 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)
```
hv_store_ent
Stores val in a hash. The hash key is specified as key . The 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 He? macros described here. Note that the caller is responsible for suitably incrementing the reference count of val before the call, and decrementing it if the function returned NULL. Effectively a successful hv_store_ent takes ownership of one reference to 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 key ; unlike val it does not take ownership of it, so maintaining the correct reference count on 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 "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied hashes.
```
	HE*	hv_store_ent(HV* tb, SV* key, SV* val, U32 hash)
```
hv_undef
Undefines the hash.
```
	void	hv_undef(HV* tb)
```
newHV
Creates a new HV. The reference count is set to 1.
```
	HV*	newHV()
```

Magical Functions

mg_clear
Clear something magical that the SV represents. See sv_magic .
```
	int	mg_clear(SV* sv)
```

mg_copy

Copies the magic from one SV to another. See sv_magic .

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

mg_find
Finds the magic pointer for type matching the SV. See sv_magic .
```
	MAGIC*	mg_find(SV* sv, int type)
```
mg_free
Free any magic storage used by the SV. See sv_magic .
```
	int	mg_free(SV* sv)
```
mg_get
Do magic after a value is retrieved from the SV. See sv_magic .
```
	int	mg_get(SV* sv)
```
mg_length
Report on the SV's length. See sv_magic .
```
	U32	mg_length(SV* sv)
```
mg_magical
Turns on the magical status of an SV. See sv_magic .
```
	void	mg_magical(SV* sv)
```
mg_set
Do magic after a value is assigned to the SV. See sv_magic .
```
	int	mg_set(SV* sv)
```
SvGETMAGIC
Invokes mg_get on an SV if it has 'get' magic. This macro evaluates its argument more than once.
```
	void	SvGETMAGIC(SV* sv)
```
SvLOCK
Arranges for a mutual exclusion lock to be obtained on sv if a suitable module has been loaded.
```
	void	SvLOCK(SV* sv)
```
SvSETMAGIC
Invokes mg_set on an SV if it has 'set' magic. This macro evaluates its argument more than once.
```
	void	SvSETMAGIC(SV* sv)
```
SvSetMagicSV
Like SvSetSV , but does any set magic required afterwards.
```
	void	SvSetMagicSV(SV* dsb, SV* ssv)
```
SvSetMagicSV_nosteal
Like SvSetSV_nosteal , but does any set magic required afterwards.
```
	void	SvSetMagicSV_nosteal(SV* dsv, SV* ssv)
```
SvSetSV
Calls sv_setsv if dsv is not the same as ssv. May evaluate arguments more than once.
```
	void	SvSetSV(SV* dsb, SV* ssv)
```
SvSetSV_nosteal
Calls a non-destructive version of sv_setsv if dsv is not the same as ssv. May evaluate arguments more than once.
```
	void	SvSetSV_nosteal(SV* dsv, SV* ssv)
```
SvSHARE
Arranges for sv to be shared between threads if a suitable module has been loaded.
```
	void	SvSHARE(SV* sv)
```
SvUNLOCK
Releases a mutual exclusion lock on sv if a suitable module has been loaded.
```
	void	SvUNLOCK(SV* sv)
```

Memory Management

Copy
The XSUB-writer's interface to the C memcpy function. The src is the source, dest is the destination, nitems is the number of items, and type is the type. May fail on overlapping copies. See also Move .
```
	void	Copy(void* src, void* dest, int nitems, type)
```
CopyD
Like Copy but returns dest. Useful for encouraging compilers to tail-call optimise.
```
	void *	CopyD(void* src, void* dest, int nitems, type)
```
Move
The XSUB-writer's interface to the C memmove function. The src is the source, dest is the destination, nitems is the number of items, and type is the type. Can do overlapping moves. See also Copy .
```
	void	Move(void* src, void* dest, int nitems, type)
```
MoveD
Like Move but returns dest. Useful for encouraging compilers to tail-call optimise.
```
	void *	MoveD(void* src, void* dest, int nitems, type)
```
Newx
The XSUB-writer's interface to the C malloc function.
```
	void	Newx(void* ptr, int nitems, type)
```
Newxc
The XSUB-writer's interface to the C malloc function, with cast.
```
	void	Newxc(void* ptr, int nitems, type, cast)
```
Newxz
The XSUB-writer's interface to the C malloc function. The allocated memory is zeroed with memzero .

In 5.9.3, we removed the 1st parameter, a debug aid, from the api. It was used to uniquely identify each usage of these allocation functions, but was deemed unnecessary with the availability of better memory tracking tools, valgrind for example.
```
	void	Newxz(void* ptr, int nitems, type)
```
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)
```
Renew
The XSUB-writer's interface to the C realloc function.
```
	void	Renew(void* ptr, int nitems, type)
```
Renewc
The XSUB-writer's interface to the C realloc function, with cast.
```
	void	Renewc(void* ptr, int nitems, type, cast)
```
Safefree
The XSUB-writer's interface to the C free function.
```
	void	Safefree(void* ptr)
```
savepv
Perl's version of strdup() . Returns a pointer to a newly allocated string which is a duplicate of pv . The size of the string is determined by strlen() . The memory allocated for the new string can be freed with the Safefree() function.
```
	char*	savepv(const char* pv)
```
savepvn
Perl's version of what strndup() would be if it existed. Returns a pointer to a newly allocated string which is a duplicate of the first len bytes from pv . The memory allocated for the new string can be freed with the Safefree() function.
```
	char*	savepvn(const char* pv, I32 len)
```
savesharedpv
A version of savepv() which allocates the duplicate string in memory which is shared between threads.
```
	char*	savesharedpv(const char* pv)
```
savesvpv
A version of savepv() /savepvn() which gets the string to duplicate from the passed in SV using SvPV()
```
	char*	savesvpv(SV* sv)
```
StructCopy
This is an architecture-independent macro to copy one structure to another.
```
	void	StructCopy(type src, type dest, type)
```
Zero
The XSUB-writer's interface to the C memzero function. The dest is the destination, nitems is the number of items, and type is the type.
```
	void	Zero(void* dest, int nitems, type)
```
ZeroD
Like Zero but returns dest. Useful for encouraging compilers to tail-call optimise.
```
	void *	ZeroD(void* dest, int nitems, type)
```

Miscellaneous Functions

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)
```
fbm_instr
Returns the location of the SV in the string delimited by str and strend . It returns Nullch if the string can't be found. The 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)
```
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, ...)
```
getcwd_sv
Fill the sv with current working directory
```
	int	getcwd_sv(SV* sv)
```
strEQ
Test two strings to see if they are equal. Returns true or false.
```
	bool	strEQ(char* s1, char* s2)
```
strGE
Test two strings to see if the first, s1 , is greater than or equal to the second, s2 . Returns true or false.
```
	bool	strGE(char* s1, char* s2)
```
strGT
Test two strings to see if the first, s1 , is greater than the second, s2 . Returns true or false.
```
	bool	strGT(char* s1, char* s2)
```
strLE
Test two strings to see if the first, s1 , is less than or equal to the second, s2 . Returns true or false.
```
	bool	strLE(char* s1, char* s2)
```
strLT
Test two strings to see if the first, s1 , is less than the second, s2 . Returns true or false.
```
	bool	strLT(char* s1, char* s2)
```
strNE
Test two strings to see if they are different. Returns true or false.
```
	bool	strNE(char* s1, char* s2)
```
strnEQ
Test two strings to see if they are equal. The len parameter indicates the number of bytes to compare. Returns true or false. (A wrapper for strncmp ).
```
	bool	strnEQ(char* s1, char* s2, STRLEN len)
```
strnNE
Test two strings to see if they are different. The len parameter indicates the number of bytes to compare. Returns true or false. (A wrapper for strncmp ).
```
	bool	strnNE(char* s1, char* s2, STRLEN len)
```
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 *)
```
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 *)
```
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 *)
```

Numeric functions

grok_bin
converts a string representing a binary number to numeric form.

On entry start and *len give the string to scan, *flags gives conversion flags, and 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 PERL_SCAN_SILENT_ILLDIGIT is set in *flags, encountering an invalid character will also trigger a warning. On return *len is set to the length of the scanned string, and *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 *result. If the value is > UV_MAX grok_bin returns UV_MAX, sets PERL_SCAN_GREATER_THAN_UV_MAX in the output flags, and writes the value to *result (or the value is discarded if result is NULL).

The binary number may optionally be prefixed with "0b" or "b" unless PERL_SCAN_DISALLOW_PREFIX is set in *flags on entry. If PERL_SCAN_ALLOW_UNDERSCORES is set in *flags then the binary number may use '_' characters to separate digits.
```
	UV	grok_bin(char* start, STRLEN* len, I32* flags, NV *result)
```
grok_hex
converts a string representing a hex number to numeric form.

On entry start and *len give the string to scan, *flags gives conversion flags, and 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 PERL_SCAN_SILENT_ILLDIGIT is set in *flags, encountering an invalid character will also trigger a warning. On return *len is set to the length of the scanned string, and *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 *result. If the value is > UV_MAX grok_hex returns UV_MAX, sets PERL_SCAN_GREATER_THAN_UV_MAX in the output flags, and writes the value to *result (or the value is discarded if result is NULL).

The hex number may optionally be prefixed with "0x" or "x" unless PERL_SCAN_DISALLOW_PREFIX is set in *flags on entry. If PERL_SCAN_ALLOW_UNDERSCORES is set in *flags then the hex number may use '_' characters to separate digits.
```
	UV	grok_hex(char* start, STRLEN* len, I32* flags, NV *result)
```
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)
```
grok_numeric_radix
Scan and skip for a numeric decimal separator (radix).
```
	bool	grok_numeric_radix(const char **sp, const char *send)
```
grok_oct
converts a string representing an octal number to numeric form.

On entry start and *len give the string to scan, *flags gives conversion flags, and 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 PERL_SCAN_SILENT_ILLDIGIT is set in *flags, encountering an invalid character will also trigger a warning. On return *len is set to the length of the scanned string, and *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 *result. If the value is > UV_MAX grok_oct returns UV_MAX, sets PERL_SCAN_GREATER_THAN_UV_MAX in the output flags, and writes the value to *result (or the value is discarded if result is NULL).

If PERL_SCAN_ALLOW_UNDERSCORES is set in *flags then the octal number may use '_' characters to separate digits.
```
	UV	grok_oct(char* start, STRLEN* len_p, I32* flags, NV *result)
```

scan_bin

For backwards compatibility. Use grok_bin instead.

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

scan_hex

For backwards compatibility. Use grok_hex instead.

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

scan_oct

For backwards compatibility. Use grok_oct instead.

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

Optree Manipulation Functions

cv_const_sv
If 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 newCONSTSUB or as described in "Constant Functions" in perlsub.
```
	SV*	cv_const_sv(CV* cv)
```
newCONSTSUB
Creates a constant sub equivalent to Perl sub FOO () { 123 } which is eligible for inlining at compile-time.
```
	CV*	newCONSTSUB(HV* stash, char* name, SV* sv)
```
newXS
Used by xsubpp to hook up XSUBs as Perl subs.

Pad Data Structures

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)
```

Stack Manipulation Macros

dMARK
Declare a stack marker variable, mark , for the XSUB. See MARK and dORIGMARK .
```
		dMARK;
```
dORIGMARK
Saves the original stack mark for the XSUB. See ORIGMARK .
```
		dORIGMARK;
```
dSP
Declares a local copy of perl's stack pointer for the XSUB, available via the SP macro. See SP .
```
		dSP;
```
EXTEND
Used to extend the argument stack for an XSUB's return values. Once used, guarantees that there is room for at least nitems to be pushed onto the stack.
```
	void	EXTEND(SP, int nitems)
```
MARK
Stack marker variable for the XSUB. See dMARK .
mPUSHi
Push an integer onto the stack. The stack must have room for this element. Handles 'set' magic. Does not use TARG . See also PUSHi , mXPUSHi and XPUSHi .
```
	void	mPUSHi(IV iv)
```
mPUSHn
Push a double onto the stack. The stack must have room for this element. Handles 'set' magic. Does not use TARG . See also PUSHn , mXPUSHn and XPUSHn .
```
	void	mPUSHn(NV nv)
```
mPUSHp
Push a string onto the stack. The stack must have room for this element. The len indicates the length of the string. Handles 'set' magic. Does not use TARG . See also PUSHp , mXPUSHp and XPUSHp .
```
	void	mPUSHp(char* str, STRLEN len)
```
mPUSHu
Push an unsigned integer onto the stack. The stack must have room for this element. Handles 'set' magic. Does not use TARG . See also PUSHu , mXPUSHu and XPUSHu .
```
	void	mPUSHu(UV uv)
```
mXPUSHi
Push an integer onto the stack, extending the stack if necessary. Handles 'set' magic. Does not use TARG . See also XPUSHi , mPUSHi and PUSHi .
```
	void	mXPUSHi(IV iv)
```
mXPUSHn
Push a double onto the stack, extending the stack if necessary. Handles 'set' magic. Does not use TARG . See also XPUSHn , mPUSHn and PUSHn .
```
	void	mXPUSHn(NV nv)
```
mXPUSHp
Push a string onto the stack, extending the stack if necessary. The len indicates the length of the string. Handles 'set' magic. Does not use TARG . See also XPUSHp , mPUSHp and PUSHp .
```
	void	mXPUSHp(char* str, STRLEN len)
```
mXPUSHu
Push an unsigned integer onto the stack, extending the stack if necessary. Handles 'set' magic. Does not use TARG . See also XPUSHu , mPUSHu and PUSHu .
```
	void	mXPUSHu(UV uv)
```
ORIGMARK
The original stack mark for the XSUB. See dORIGMARK .
POPi
Pops an integer off the stack.
```
	IV	POPi
```
POPl
Pops a long off the stack.
```
	long	POPl
```
POPn
Pops a double off the stack.
```
	NV	POPn
```
POPp
Pops a string off the stack. Deprecated. New code should use POPpx.
```
	char*	POPp
```
POPpbytex
Pops a string off the stack which must consist of bytes i.e. characters < 256.
```
	char*	POPpbytex
```
POPpx
Pops a string off the stack.
```
	char*	POPpx
```
POPs
Pops an SV off the stack.
```
	SV*	POPs
```
PUSHi
Push an integer onto the stack. The stack must have room for this element. Handles 'set' magic. Uses TARG , so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG -oriented macros to return lists from XSUB's - see mPUSHi instead. See also XPUSHi and mXPUSHi .
```
	void	PUSHi(IV iv)
```
PUSHMARK
Opening bracket for arguments on a callback. See PUTBACK and perlcall.
```
	void	PUSHMARK(SP)
```
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 TARG . See also PUSHs , XPUSHmortal and XPUSHs .
```
	void	PUSHmortal()
```
PUSHn
Push a double onto the stack. The stack must have room for this element. Handles 'set' magic. Uses TARG , so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG -oriented macros to return lists from XSUB's - see mPUSHn instead. See also XPUSHn and mXPUSHn .
```
	void	PUSHn(NV nv)
```
PUSHp
Push a string onto the stack. The stack must have room for this element. The len indicates the length of the string. Handles 'set' magic. Uses TARG , so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG -oriented macros to return lists from XSUB's - see mPUSHp instead. See also XPUSHp and mXPUSHp .
```
	void	PUSHp(char* str, STRLEN len)
```
PUSHs
Push an SV onto the stack. The stack must have room for this element. Does not handle 'set' magic. Does not use TARG . See also PUSHmortal , XPUSHs and XPUSHmortal .
```
	void	PUSHs(SV* sv)
```
PUSHu
Push an unsigned integer onto the stack. The stack must have room for this element. Handles 'set' magic. Uses TARG , so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG -oriented macros to return lists from XSUB's - see mPUSHu instead. See also XPUSHu and mXPUSHu .
```
	void	PUSHu(UV uv)
```
PUTBACK
Closing bracket for XSUB arguments. This is usually handled by xsubpp . See PUSHMARK and perlcall for other uses.
```
		PUTBACK;
```
SP
Stack pointer. This is usually handled by xsubpp . See dSP and SPAGAIN .
SPAGAIN
Refetch the stack pointer. Used after a callback. See perlcall.
```
		SPAGAIN;
```
XPUSHi
Push an integer onto the stack, extending the stack if necessary. Handles 'set' magic. Uses TARG , so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG -oriented macros to return lists from XSUB's - see mXPUSHi instead. See also PUSHi and mPUSHi .
```
	void	XPUSHi(IV iv)
```
XPUSHmortal
Push a new mortal SV onto the stack, extending the stack if necessary. Does not handle 'set' magic. Does not use TARG . See also XPUSHs , PUSHmortal and PUSHs .
```
	void	XPUSHmortal()
```
XPUSHn
Push a double onto the stack, extending the stack if necessary. Handles 'set' magic. Uses TARG , so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG -oriented macros to return lists from XSUB's - see mXPUSHn instead. See also PUSHn and mPUSHn .
```
	void	XPUSHn(NV nv)
```
XPUSHp
Push a string onto the stack, extending the stack if necessary. The len indicates the length of the string. Handles 'set' magic. Uses TARG , so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG -oriented macros to return lists from XSUB's - see mXPUSHp instead. See also PUSHp and mPUSHp .
```
	void	XPUSHp(char* str, STRLEN len)
```
XPUSHs
Push an SV onto the stack, extending the stack if necessary. Does not handle 'set' magic. Does not use TARG . See also XPUSHmortal , PUSHs and PUSHmortal .
```
	void	XPUSHs(SV* sv)
```
XPUSHu
Push an unsigned integer onto the stack, extending the stack if necessary. Handles 'set' magic. Uses TARG , so dTARGET or dXSTARG should be called to declare it. Do not call multiple TARG -oriented macros to return lists from XSUB's - see mXPUSHu instead. See also PUSHu and mPUSHu .
```
	void	XPUSHu(UV uv)
```
XSRETURN
Return from XSUB, indicating number of items on the stack. This is usually handled by xsubpp .
```
	void	XSRETURN(int nitems)
```
XSRETURN_EMPTY
Return an empty list from an XSUB immediately.
```
		XSRETURN_EMPTY;
```
XSRETURN_IV
Return an integer from an XSUB immediately. Uses XST_mIV .
```
	void	XSRETURN_IV(IV iv)
```
XSRETURN_NO
Return &PL_sv_no from an XSUB immediately. Uses XST_mNO .
```
		XSRETURN_NO;
```
XSRETURN_NV
Return a double from an XSUB immediately. Uses XST_mNV .
```
	void	XSRETURN_NV(NV nv)
```
XSRETURN_PV
Return a copy of a string from an XSUB immediately. Uses XST_mPV .
```
	void	XSRETURN_PV(char* str)
```
XSRETURN_UNDEF
Return &PL_sv_undef from an XSUB immediately. Uses XST_mUNDEF .
```
		XSRETURN_UNDEF;
```
XSRETURN_UV
Return an integer from an XSUB immediately. Uses XST_mUV .
```
	void	XSRETURN_UV(IV uv)
```
XSRETURN_YES
Return &PL_sv_yes from an XSUB immediately. Uses XST_mYES .
```
		XSRETURN_YES;
```
XST_mIV
Place an integer into the specified position pos on the stack. The value is stored in a new mortal SV.
```
	void	XST_mIV(int pos, IV iv)
```
XST_mNO
Place &PL_sv_no into the specified position pos on the stack.
```
	void	XST_mNO(int pos)
```
XST_mNV
Place a double into the specified position pos on the stack. The value is stored in a new mortal SV.
```
	void	XST_mNV(int pos, NV nv)
```
XST_mPV
Place a copy of a string into the specified position pos on the stack. The value is stored in a new mortal SV.
```
	void	XST_mPV(int pos, char* str)
```
XST_mUNDEF
Place &PL_sv_undef into the specified position pos on the stack.
```
	void	XST_mUNDEF(int pos)
```
XST_mYES
Place &PL_sv_yes into the specified position pos on the stack.
```
	void	XST_mYES(int pos)
```

SV Flags

svtype
An enum of flags for Perl types. These are found in the file sv.h in the svtype enum. Test these flags with the SvTYPE macro.
SVt_IV
Integer type flag for scalars. See svtype .
SVt_NV
Double type flag for scalars. See svtype .
SVt_PV
Pointer type flag for scalars. See svtype .
SVt_PVAV
Type flag for arrays. See svtype .
SVt_PVCV
Type flag for code refs. See svtype .
SVt_PVHV
Type flag for hashes. See svtype .
SVt_PVMG
Type flag for blessed scalars. See svtype .

SV Manipulation Functions

get_sv
Returns the SV of the specified Perl scalar. If create is set and the Perl variable does not exist then it will be created. If 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)
```
looks_like_number
Test if the content of an SV looks like a number (or is a number). Inf and 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)
```
newRV_inc
Creates an RV wrapper for an SV. The reference count for the original SV is incremented.
```
	SV*	newRV_inc(SV* sv)
```
newRV_noinc
Creates an RV wrapper for an SV. The reference count for the original SV is not incremented.
```
	SV*	newRV_noinc(SV *sv)
```
NEWSV
Creates a new SV. A non-zero 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. id is an integer id between 0 and 1299 (used to identify leaks).
```
	SV*	NEWSV(int id, STRLEN len)
```
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 NEWSV macro.
```
	SV*	newSV(STRLEN len)
```
newSVhek
Creates a new SV from the hash key structure. It will generate scalars that point to the shared string table where possible. Returns a new (undefined) SV if the hek is NULL.
```
	SV*	newSVhek(const HEK *hek)
```
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)
```
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)
```
newSVpv
Creates a new SV and copies a string into it. The reference count for the SV is set to 1. If len is zero, Perl will compute the length using strlen(). For efficiency, consider using newSVpvn instead.
```
	SV*	newSVpv(const char* s, STRLEN len)
```
newSVpvf
Creates a new SV and initializes it with the string formatted like sprintf.
```
	SV*	newSVpvf(const char* pat, ...)
```
newSVpvn
Creates a new SV and copies a string into it. The reference count for the SV is set to 1. Note that if len is zero, Perl will create a zero length string. You are responsible for ensuring that the source string is at least len bytes long. If the s argument is NULL the new SV will be undefined.
```
	SV*	newSVpvn(const char* s, STRLEN len)
```
newSVpvn_share
Creates a new SV with its SvPVX_const 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 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_const == HeKEY and hash lookup will avoid string compare.
```
	SV*	newSVpvn_share(const char* s, I32 len, U32 hash)
```
newSVrv
Creates a new SV for the RV, rv , to point to. If rv is not an RV then it will be upgraded to one. If 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)
```
newSVsv
Creates a new SV which is an exact duplicate of the original SV. (Uses sv_setsv ).
```
	SV*	newSVsv(SV* old)
```
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)
```
SvCUR
Returns the length of the string which is in the SV. See SvLEN .
```
	STRLEN	SvCUR(SV* sv)
```
SvCUR_set
Set the current length of the string which is in the SV. See SvCUR and SvIV_set .
```
	void	SvCUR_set(SV* sv, STRLEN len)
```
SvEND
Returns a pointer to the last character in the string which is in the SV. See SvCUR . Access the character as *(SvEND(sv)).
```
	char*	SvEND(SV* sv)
```
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 sv_grow to perform the expansion if necessary. Returns a pointer to the character buffer.
```
	char *	SvGROW(SV* sv, STRLEN len)
```
SvIOK
Returns a boolean indicating whether the SV contains an integer.
```
	bool	SvIOK(SV* sv)
```
SvIOKp
Returns a boolean indicating whether the SV contains an integer. Checks the private setting. Use SvIOK .
```
	bool	SvIOKp(SV* sv)
```
SvIOK_notUV
Returns a boolean indicating whether the SV contains a signed integer.
```
	bool	SvIOK_notUV(SV* sv)
```
SvIOK_off
Unsets the IV status of an SV.
```
	void	SvIOK_off(SV* sv)
```
SvIOK_on
Tells an SV that it is an integer.
```
	void	SvIOK_on(SV* sv)
```
SvIOK_only
Tells an SV that it is an integer and disables all other OK bits.
```
	void	SvIOK_only(SV* sv)
```
SvIOK_only_UV
Tells and SV that it is an unsigned integer and disables all other OK bits.
```
	void	SvIOK_only_UV(SV* sv)
```
SvIOK_UV
Returns a boolean indicating whether the SV contains an unsigned integer.
```
	bool	SvIOK_UV(SV* sv)
```
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)
```
SvIsCOW_shared_hash
Returns a boolean indicating whether the SV is Copy-On-Write shared hash key scalar.
```
	bool	SvIsCOW_shared_hash(SV* sv)
```
SvIV
Coerces the given SV to an integer and returns it. See SvIVx for a version which guarantees to evaluate sv only once.
```
	IV	SvIV(SV* sv)
```
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 SvIV() .
```
	IV	SvIVX(SV* sv)
```
SvIVx
Coerces the given SV to an integer and returns it. Guarantees to evaluate sv only once. Use the more efficient SvIV otherwise.
```
	IV	SvIVx(SV* sv)
```
SvIV_set
Set the value of the IV pointer in sv to val. It is possible to perform the same function of this macro with an lvalue assignment to SvIVX . With future Perls, however, it will be more efficient to use SvIV_set instead of the lvalue assignment to SvIVX .
```
	void	SvIV_set(SV* sv, IV val)
```
SvLEN
Returns the size of the string buffer in the SV, not including any part attributable to SvOOK . See SvCUR .
```
	STRLEN	SvLEN(SV* sv)
```
SvLEN_set
Set the actual length of the string which is in the SV. See SvIV_set .
```
	void	SvLEN_set(SV* sv, STRLEN len)
```
SvMAGIC_set
Set the value of the MAGIC pointer in sv to val. See SvIV_set .
```
	void	SvMAGIC_set(SV* sv, MAGIC* val)
```
SvNIOK
Returns a boolean indicating whether the SV contains a number, integer or double.
```
	bool	SvNIOK(SV* sv)
```
SvNIOKp
Returns a boolean indicating whether the SV contains a number, integer or double. Checks the private setting. Use SvNIOK .
```
	bool	SvNIOKp(SV* sv)
```
SvNIOK_off
Unsets the NV/IV status of an SV.
```
	void	SvNIOK_off(SV* sv)
```
SvNOK
Returns a boolean indicating whether the SV contains a double.
```
	bool	SvNOK(SV* sv)
```
SvNOKp
Returns a boolean indicating whether the SV contains a double. Checks the private setting. Use SvNOK .
```
	bool	SvNOKp(SV* sv)
```
SvNOK_off
Unsets the NV status of an SV.
```
	void	SvNOK_off(SV* sv)
```
SvNOK_on
Tells an SV that it is a double.
```
	void	SvNOK_on(SV* sv)
```
SvNOK_only
Tells an SV that it is a double and disables all other OK bits.
```
	void	SvNOK_only(SV* sv)
```
SvNV
Coerce the given SV to a double and return it. See SvNVx for a version which guarantees to evaluate sv only once.
```
	NV	SvNV(SV* sv)
```
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 SvNV() .
```
	NV	SvNVX(SV* sv)
```
SvNVx
Coerces the given SV to a double and returns it. Guarantees to evaluate sv only once. Use the more efficient SvNV otherwise.
```
	NV	SvNVx(SV* sv)
```
SvNV_set
Set the value of the NV pointer in sv to val. See SvIV_set .
```
	void	SvNV_set(SV* sv, NV val)
```
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)
```
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)
```
SvPOK
Returns a boolean indicating whether the SV contains a character string.
```
	bool	SvPOK(SV* sv)
```
SvPOKp
Returns a boolean indicating whether the SV contains a character string. Checks the private setting. Use SvPOK .
```
	bool	SvPOKp(SV* sv)
```
SvPOK_off
Unsets the PV status of an SV.
```
	void	SvPOK_off(
```