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# perlapi

- NAME
- DESCRIPTION
- 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.

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. `flags` is currently ignored.

      	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 the section on Understanding the Magic of Tied Hashes and Arrays in the perlguts manpage 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 the section on Understanding the Magic of Tied Hashes and Arrays in the perlguts manpage 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)

bytes_from_utf8
  Converts a string `s` of length `len` from UTF8 into byte encoding. Unlike <utf8_to_bytes> but like `bytes_to_utf8`, returns a pointer to the newly-created string, and updates `len` to contain the new length. Returns the original string if no conversion occurs, `len` is unchanged. Do nothing if `is_utf8` points to 0. Sets `is_utf8` to 0 if `s` is converted or contains all 7bit characters.

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

      	U8*	bytes_from_utf8(U8 *s, STRLEN *len, bool *is_utf8)

bytes_to_utf8
  Converts a string `s` of length `len` from ASCII into UTF8 encoding. Returns a pointer to the newly-created string, and sets `len` to reflect the new length.

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

      	U8*	bytes_to_utf8(U8 *s, STRLEN *len)

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

      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 the perlcall manpage.

      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 the perlcall manpage.

      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 the perlcall manpage.

      NOTE: the perl_ form of this function is deprecated.

      	I32	call_sv(SV* sv, I32 flags)

CLASS
  Variable which is setup by `xsubpp` to indicate the class name for a C++ XS constructor. This is always a `char*`. See `THIS`.

      	char*	CLASS

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)

croak
  This is the XSUB-writer's interface to Perl's `die` function. Normally use this function the same way you use the C `printf` function. See `warn`.

      If you want to throw an exception object, assign the object to
      $@ and then pass Nullch to croak():

         errsv = get_sv("@", TRUE);
         sv_setsv(errsv, exception_object);
         croak(Nullch);

      	void	croak(const char* pat, ...)

CvSTASH
  Returns the stash of the CV.

      	HV*	CvSTASH(CV* cv)

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;

dXSARGS
  Sets up stack and mark pointers for an XSUB, calling dSP and dMARK. This is usually handled automatically by `xsubpp`. Declares the `items` variable to indicate the number of items on the stack.

      		dXSARGS;

dXSI32
  Sets up the `ix` variable for an XSUB which has aliases. This is usually handled automatically by `xsubpp`.

      		dXSI32;

ENTER
  Opening bracket on a callback. See `LEAVE` and the perlcall manpage.

      		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)

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)

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)

FREETMPS
  Closing bracket for temporaries on a callback. See `SAVETMPS` and the perlcall manpage.

      		FREETMPS;

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)

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)

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)

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)

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

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 the gv_fetchmethod_autoload manpage.

      	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_stashpv
  Returns a pointer to the stash for a specified package. `name` should be a valid UTF-8 string. 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_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)

G_ARRAY
  Used to indicate list context. See `GIMME_V`, `GIMME` and the perlcall manpage.
G_DISCARD
  Indicates that arguments returned from a callback should be discarded. See the perlcall manpage.
G_EVAL
  Used to force a Perl `eval` wrapper around a callback. See the perlcall manpage.
G_NOARGS
  Indicates that no arguments are being sent to a callback. See the perlcall manpage.
G_SCALAR
  Used to indicate scalar context. See `GIMME_V`, `GIMME`, and the perlcall manpage.
G_VOID
  Used to indicate void context. See `GIMME_V` and the perlcall manpage.
HEf_SVKEY
  This flag, used in the length slot of hash entries and magic structures, specifies the structure contains a `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_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, U32 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, U32 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 a `SV*`.

      See the section on Understanding the Magic of Tied Hashes and Arrays in the perlguts manpage for more
      information on how to use this function on tied hashes.

      	SV**	hv_fetch(HV* tb, const char* key, U32 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 the section on Understanding the Magic of Tied Hashes and Arrays in the perlguts manpage 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`.

      	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_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_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.

      See the section on Understanding the Magic of Tied Hashes and Arrays in the perlguts manpage for more
      information on how to use this function on tied hashes.

      	SV**	hv_store(HV* tb, const char* key, U32 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.

      See the section on Understanding the Magic of Tied Hashes and Arrays in the perlguts manpage 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)

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)

is_utf8_char
  Tests if some arbitrary number of bytes begins in a valid UTF-8 character. The actual number of bytes in the UTF-8 character will be returned if it is valid, otherwise 0.

      	STRLEN	is_utf8_char(U8 *p)

is_utf8_string
  Returns true if first `len` bytes of the given string form valid a UTF8 string, false otherwise.

      	bool	is_utf8_string(U8 *s, STRLEN len)

items
  Variable which is setup by `xsubpp` to indicate the number of items on the stack. See the section on Variable-length Parameter Lists in the perlxs manpage.

      	I32	items

ix
  Variable which is setup by `xsubpp` to indicate which of an XSUB's aliases was used to invoke it. See the section on The ALIAS: Keyword in the perlxs manpage.

      	I32	ix

LEAVE
  Closing bracket on a callback. See `ENTER` and the perlcall manpage.

      		LEAVE;

looks_like_number
  Test if an the content of an SV looks like a number (or is a number).

      	I32	looks_like_number(SV* sv)

MARK
  Stack marker variable for the XSUB. See `dMARK`.
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)

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)

New
  The XSUB-writer's interface to the C `malloc` function.

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

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

      	AV*	newAV()

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

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

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

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

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

      	HV*	newHV()

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)

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 an initialize 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.

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

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.

      	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)

newXS
  Used by `xsubpp` to hook up XSUBs as Perl subs.
newXSproto
  Used by `xsubpp` to hook up XSUBs as Perl subs. Adds Perl prototypes to the subs.
Newz
  The XSUB-writer's interface to the C `malloc` function. The allocated memory is zeroed with `memzero`.

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

Nullav
  Null AV pointer.
Nullch
  Null character pointer.
Nullcv
  Null CV pointer.
Nullhv
  Null HV pointer.
Nullsv
  Null SV pointer.
ORIGMARK
  The original stack mark for the XSUB. See `dORIGMARK`.
perl_alloc
  Allocates a new Perl interpreter. See the perlembed manpage.

      	PerlInterpreter*	perl_alloc()

perl_construct
  Initializes a new Perl interpreter. See the perlembed manpage.

      	void	perl_construct(PerlInterpreter* interp)

perl_destruct
  Shuts down a Perl interpreter. See the perlembed manpage.

      	void	perl_destruct(PerlInterpreter* interp)

perl_free
  Releases a Perl interpreter. See the perlembed manpage.

      	void	perl_free(PerlInterpreter* interp)

perl_parse
  Tells a Perl interpreter to parse a Perl script. See the perlembed manpage.

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

perl_run
  Tells a Perl interpreter to run. See the perlembed manpage.

      	int	perl_run(PerlInterpreter* interp)

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

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.

      	char*	POPp

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. See `XPUSHi`.

      	void	PUSHi(IV iv)

PUSHMARK
  Opening bracket for arguments on a callback. See `PUTBACK` and the perlcall manpage.

      		PUSHMARK;

PUSHn
  Push a double onto the stack. The stack must have room for this element. Handles 'set' magic. See `XPUSHn`.

      	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. See `XPUSHp`.

      	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. See `XPUSHs`.

      	void	PUSHs(SV* sv)

PUSHu
  Push an unsigned integer onto the stack. The stack must have room for this element. See `XPUSHu`.

      	void	PUSHu(UV uv)

PUTBACK
  Closing bracket for XSUB arguments. This is usually handled by `xsubpp`. See `PUSHMARK` and the perlcall manpage for other uses.

      		PUTBACK;

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)

require_pv
  Tells Perl to `require` a module.

      NOTE: the perl_ form of this function is deprecated.

      	void	require_pv(const char* pv)

RETVAL
  Variable which is setup by `xsubpp` to hold the return value for an XSUB. This is always the proper type for the XSUB. See the section on The RETVAL Variable in the perlxs manpage.

      	(whatever)	RETVAL

Safefree
  The XSUB-writer's interface to the C `free` function.

      	void	Safefree(void* ptr)

savepv
  Copy a string to a safe spot. This does not use an SV.

      	char*	savepv(const char* sv)

savepvn
  Copy a string to a safe spot. The `len` indicates number of bytes to copy. This does not use an SV.

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

SAVETMPS
  Opening bracket for temporaries on a callback. See `FREETMPS` and the perlcall manpage.

      		SAVETMPS;

SP
  Stack pointer. This is usually handled by `xsubpp`. See `dSP` and `SPAGAIN`.
SPAGAIN
  Refetch the stack pointer. Used after a callback. See the perlcall manpage.

      		SPAGAIN;

ST
  Used to access elements on the XSUB's stack.

      	SV*	ST(int ix)

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)

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

      	void	StructCopy(type src, type dest, type)

SvCUR
  Returns the length of the string which is in the SV. See `SvLEN`.

      	STRLEN	SvCUR(SV* sv)

SvCUR_set
  Set the length of the string which is in the SV. See `SvCUR`.

      	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)

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

      	void	SvGETMAGIC(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.

      	void	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 an signed integer.

      	void	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.

      	void	SvIOK_UV(SV* sv)

SvIV
  Coerces the given SV to an integer and returns it.

      	IV	SvIV(SV* sv)

SvIVX
  Returns the integer which is stored in the SV, assuming SvIOK is true.

      	IV	SvIVX(SV* sv)

SvLEN
  Returns the size of the string buffer in the SV, not including any part attributable to `SvOOK`. See `SvCUR`.

      	STRLEN	SvLEN(SV* sv)

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.

      	NV	SvNV(SV* sv)

SvNVX
  Returns the double which is stored in the SV, assuming SvNOK is true.

      	NV	SvNVX(SV* sv)

SvOK
  Returns a boolean indicating whether the value is an SV.

      	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(SV* sv)

SvPOK_on
  Tells an SV that it is a string.

      	void	SvPOK_on(SV* sv)

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

      	void	SvPOK_only(SV* sv)

SvPOK_only_UTF8
  Tells an SV that it is a UTF8 string (do not use frivolously) and disables all other OK bits.

      	void	SvPOK_only_UTF8(SV* sv)

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. Handles 'get' magic.

      	char*	SvPV(SV* sv, STRLEN len)

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

      	char*	SvPVX(SV* sv)

SvPV_force
  Like <SvPV> but will force the SV into becoming a string (SvPOK). You want force if you are going to update the SvPVX directly.

      	char*	SvPV_force(SV* sv, STRLEN len)

SvPV_nolen
  Returns a pointer to the string in the SV, or a stringified form of the SV if the SV does not contain a string. Handles 'get' magic.

      	char*	SvPV_nolen(SV* sv)

SvREFCNT
  Returns the value of the object's reference count.

      	U32	SvREFCNT(SV* sv)

SvREFCNT_dec
  Decrements the reference count of the given SV.

      	void	SvREFCNT_dec(SV* sv)

SvREFCNT_inc
  Increments the reference count of the given SV.

      	SV*	SvREFCNT_inc(SV* sv)

SvROK
  Tests if the SV is an RV.

      	bool	SvROK(SV* sv)

SvROK_off
  Unsets the RV status of an SV.

      	void	SvROK_off(SV* sv)

SvROK_on
  Tells an SV that it is an RV.

      	void	SvROK_on(SV* sv)

SvRV
  Dereferences an RV to return the SV.

      	SV*	SvRV(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)

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)

SvSTASH
  Returns the stash of the SV.

      	HV*	SvSTASH(SV* sv)

SvTAINT
  Taints an SV if tainting is enabled

      	void	SvTAINT(SV* sv)

SvTAINTED
  Checks to see if an SV is tainted. Returns TRUE if it is, FALSE if not.

      	bool	SvTAINTED(SV* sv)

SvTAINTED_off
  Untaints an SV. Be very careful with this routine, as it short-circuits some of Perl's fundamental security features. XS module authors should not use this function unless they fully understand all the implications of unconditionally untainting the value. Untainting should be done in the standard perl fashion, via a carefully crafted regexp, rather than directly untainting variables.

      	void	SvTAINTED_off(SV* sv)

SvTAINTED_on
  Marks an SV as tainted.

      	void	SvTAINTED_on(SV* sv)

SvTRUE
  Returns a boolean indicating whether Perl would evaluate the SV as true or false, defined or undefined. Does not handle 'get' magic.

      	bool	SvTRUE(SV* sv)

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.
SvTYPE
  Returns the type of the SV. See `svtype`.

      	svtype	SvTYPE(SV* sv)

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`.
SvUPGRADE
  Used to upgrade an SV to a more complex form. Uses `sv_upgrade` to perform the upgrade if necessary. See `svtype`.

      	void	SvUPGRADE(SV* sv, svtype type)

SvUTF8
  Returns a boolean indicating whether the SV contains UTF-8 encoded data.

      	void	SvUTF8(SV* sv)

SvUTF8_off
  Unsets the UTF8 status of an SV.

      	void	SvUTF8_off(SV *sv)

SvUTF8_on
  Tells an SV that it is a string and encoded in UTF8. Do not use frivolously.

      	void	SvUTF8_on(SV *sv)

SvUV
  Coerces the given SV to an unsigned integer and returns it.

      	UV	SvUV(SV* sv)

SvUVX
  Returns the unsigned integer which is stored in the SV, assuming SvIOK is true.

      	UV	SvUVX(SV* sv)

sv_2mortal
  Marks an SV as mortal. The SV will be destroyed when the current context ends.

      	SV*	sv_2mortal(SV* sv)

sv_bless
  Blesses an SV into a specified package. The SV must be an RV. The package must be designated by its stash (see `gv_stashpv()`). The reference count of the SV is unaffected.

      	SV*	sv_bless(SV* sv, HV* stash)

sv_catpv
  Concatenates the string onto the end of the string which is in the SV. Handles 'get' magic, but not 'set' magic. See `sv_catpv_mg`.

      	void	sv_catpv(SV* sv, const char* ptr)

sv_catpvf
  Processes its arguments like `sprintf` and appends the formatted output to an SV. Handles 'get' magic, but not 'set' magic. `SvSETMAGIC()` must typically be called after calling this function to handle 'set' magic.

      	void	sv_catpvf(SV* sv, const char* pat, ...)

sv_catpvf_mg
  Like `sv_catpvf`, but also handles 'set' magic.

      	void	sv_catpvf_mg(SV *sv, const char* pat, ...)

sv_catpvn
  Concatenates the string onto the end of the string which is in the SV. The `len` indicates number of bytes to copy. Handles 'get' magic, but not 'set' magic. See `sv_catpvn_mg`.

      	void	sv_catpvn(SV* sv, const char* ptr, STRLEN len)

sv_catpvn_mg
  Like `sv_catpvn`, but also handles 'set' magic.

      	void	sv_catpvn_mg(SV *sv, const char *ptr, STRLEN len)

sv_catpv_mg
  Like `sv_catpv`, but also handles 'set' magic.

      	void	sv_catpv_mg(SV *sv, const char *ptr)

sv_catsv
  Concatenates the string from SV `ssv` onto the end of the string in SV `dsv`. Modifies `dsv` but not `ssv`. Handles 'get' magic, but not 'set' magic. See `sv_catsv_mg`.

      	void	sv_catsv(SV* dsv, SV* ssv)

sv_catsv_mg
  Like `sv_catsv`, but also handles 'set' magic.

      	void	sv_catsv_mg(SV *dstr, SV *sstr)

sv_chop
  Efficient removal of characters from the beginning of the string buffer. SvPOK(sv) must be true and the `ptr` must be a pointer to somewhere inside the string buffer. The `ptr` becomes the first character of the adjusted string.

      	void	sv_chop(SV* sv, char* ptr)

sv_clear
  Clear an SV, making it empty. Does not free the memory used by the SV itself.

      	void	sv_clear(SV* sv)

sv_cmp
  Compares the strings in two SVs. Returns -1, 0, or 1 indicating whether the string in `sv1` is less than, equal to, or greater than the string in `sv2`.

      	I32	sv_cmp(SV* sv1, SV* sv2)

sv_cmp_locale
  Compares the strings in two SVs in a locale-aware manner. See the sv_cmp_locale entry elsewhere in this document

      	I32	sv_cmp_locale(SV* sv1, SV* sv2)

sv_dec
  Auto-decrement of the value in the SV.

      	void	sv_dec(SV* sv)

sv_derived_from
  Returns a boolean indicating whether the SV is derived from the specified class. This is the function that implements `UNIVERSAL::isa`. It works for class names as well as for objects.

      	bool	sv_derived_from(SV* sv, const char* name)

sv_eq
  Returns a boolean indicating whether the strings in the two SVs are identical.

      	I32	sv_eq(SV* sv1, SV* sv2)

sv_free
  Free the memory used by an SV.

      	void	sv_free(SV* sv)

sv_gets
  Get a line from the filehandle and store it into the SV, optionally appending to the currently-stored string.

      	char*	sv_gets(SV* sv, PerlIO* fp, I32 append)

sv_grow
  Expands the character buffer in the SV. This will use `sv_unref` and will upgrade the SV to `SVt_PV`. Returns a pointer to the character buffer. Use `SvGROW`.

      	char*	sv_grow(SV* sv, STRLEN newlen)

sv_inc
  Auto-increment of the value in the SV.

      	void	sv_inc(SV* sv)

sv_insert
  Inserts a string at the specified offset/length within the SV. Similar to the Perl substr() function.

      	void	sv_insert(SV* bigsv, STRLEN offset, STRLEN len, char* little, STRLEN littlelen)

sv_isa
  Returns a boolean indicating whether the SV is blessed into the specified class. This does not check for subtypes; use `sv_derived_from` to verify an inheritance relationship.

      	int	sv_isa(SV* sv, const char* name)

sv_isobject
  Returns a boolean indicating whether the SV is an RV pointing to a blessed object. If the SV is not an RV, or if the object is not blessed, then this will return false.

      	int	sv_isobject(SV* sv)

sv_len
  Returns the length of the string in the SV. See also `SvCUR`.

      	STRLEN	sv_len(SV* sv)

sv_len_utf8
  Returns the number of characters in the string in an SV, counting wide UTF8 bytes as a single character.

      	STRLEN	sv_len_utf8(SV* sv)

sv_magic
  Adds magic to an SV.

      	void	sv_magic(SV* sv, SV* obj, int how, const char* name, I32 namlen)

sv_mortalcopy
  Creates a new SV which is a copy of the original SV. The new SV is marked as mortal.

      	SV*	sv_mortalcopy(SV* oldsv)

sv_newmortal
  Creates a new SV which is mortal. The reference count of the SV is set to 1.

      	SV*	sv_newmortal()

sv_pvn_force
  Get a sensible string out of the SV somehow.

      	char*	sv_pvn_force(SV* sv, STRLEN* lp)

sv_pvutf8n_force
  Get a sensible UTF8-encoded string out of the SV somehow. See the sv_pvn_force entry elsewhere in this document.

      	char*	sv_pvutf8n_force(SV* sv, STRLEN* lp)

sv_reftype
  Returns a string describing what the SV is a reference to.

      	char*	sv_reftype(SV* sv, int ob)

sv_replace
  Make the first argument a copy of the second, then delete the original.

      	void	sv_replace(SV* sv, SV* nsv)

sv_rvweaken
  Weaken a reference.

      	SV*	sv_rvweaken(SV *sv)

sv_setiv
  Copies an integer into the given SV. Does not handle 'set' magic. See `sv_setiv_mg`.

      	void	sv_setiv(SV* sv, IV num)

sv_setiv_mg
  Like `sv_setiv`, but also handles 'set' magic.

      	void	sv_setiv_mg(SV *sv, IV i)

sv_setnv
  Copies a double into the given SV. Does not handle 'set' magic. See `sv_setnv_mg`.

      	void	sv_setnv(SV* sv, NV num)

sv_setnv_mg
  Like `sv_setnv`, but also handles 'set' magic.

      	void	sv_setnv_mg(SV *sv, NV num)

sv_setpv
  Copies a string into an SV. The string must be null-terminated. Does not handle 'set' magic. See `sv_setpv_mg`.

      	void	sv_setpv(SV* sv, const char* ptr)

sv_setpvf
  Processes its arguments like `sprintf` and sets an SV to the formatted output. Does not handle 'set' magic. See `sv_setpvf_mg`.

      	void	sv_setpvf(SV* sv, const char* pat, ...)

sv_setpvf_mg
  Like `sv_setpvf`, but also handles 'set' magic.

      	void	sv_setpvf_mg(SV *sv, const char* pat, ...)

sv_setpviv
  Copies an integer into the given SV, also updating its string value. Does not handle 'set' magic. See `sv_setpviv_mg`.

      	void	sv_setpviv(SV* sv, IV num)

sv_setpviv_mg
  Like `sv_setpviv`, but also handles 'set' magic.

      	void	sv_setpviv_mg(SV *sv, IV iv)

sv_setpvn
  Copies a string into an SV. The `len` parameter indicates the number of bytes to be copied. Does not handle 'set' magic. See `sv_setpvn_mg`.

      	void	sv_setpvn(SV* sv, const char* ptr, STRLEN len)

sv_setpvn_mg
  Like `sv_setpvn`, but also handles 'set' magic.

      	void	sv_setpvn_mg(SV *sv, const char *ptr, STRLEN len)

sv_setpv_mg
  Like `sv_setpv`, but also handles 'set' magic.

      	void	sv_setpv_mg(SV *sv, const char *ptr)

sv_setref_iv
  Copies an integer into a new SV, optionally blessing the SV. The `rv` argument will be upgraded to an RV. That RV will be modified to point to the new SV. The `classname` argument indicates the package for the blessing. Set `classname` to `Nullch` to avoid the blessing. The new SV will be returned and will have a reference count of 1.

      	SV*	sv_setref_iv(SV* rv, const char* classname, IV iv)

sv_setref_nv
  Copies a double into a new SV, optionally blessing the SV. The `rv` argument will be upgraded to an RV. That RV will be modified to point to the new SV. The `classname` argument indicates the package for the blessing. Set `classname` to `Nullch` to avoid the blessing. The new SV will be returned and will have a reference count of 1.

      	SV*	sv_setref_nv(SV* rv, const char* classname, NV nv)

sv_setref_pv
  Copies a pointer into a new SV, optionally blessing the SV. The `rv` argument will be upgraded to an RV. That RV will be modified to point to the new SV. If the `pv` argument is NULL then `PL_sv_undef` will be placed into the SV. The `classname` argument indicates the package for the blessing. Set `classname` to `Nullch` to avoid the blessing. The new SV will be returned and will have a reference count of 1.

  Do not use with other Perl types such as HV, AV, SV, CV, because those objects will become corrupted by the pointer copy process.

      Note that sv_setref_pvn copies the string while this copies the pointer.

      	SV*	sv_setref_pv(SV* rv, const char* classname, void* pv)

sv_setref_pvn
  Copies a string into a new SV, optionally blessing the SV. The length of the string must be specified with `n`. The `rv` argument will be upgraded to an RV. That RV will be modified to point to the new SV. The `classname` argument indicates the package for the blessing. Set `classname` to `Nullch` to avoid the blessing. The new SV will be returned and will have a reference count of 1.

      Note that sv_setref_pv copies the pointer while this copies the string.

      	SV*	sv_setref_pvn(SV* rv, const char* classname, char* pv, STRLEN n)

sv_setsv
  Copies the contents of the source SV `ssv` into the destination SV `dsv`. The source SV may be destroyed if it is mortal. Does not handle 'set' magic. See the macro forms `SvSetSV`, `SvSetSV_nosteal` and `sv_setsv_mg`.

      	void	sv_setsv(SV* dsv, SV* ssv)

sv_setsv_mg
  Like `sv_setsv`, but also handles 'set' magic.

      	void	sv_setsv_mg(SV *dstr, SV *sstr)

sv_setuv
  Copies an unsigned integer into the given SV. Does not handle 'set' magic. See `sv_setuv_mg`.

      	void	sv_setuv(SV* sv, UV num)

sv_setuv_mg
  Like `sv_setuv`, but also handles 'set' magic.

      	void	sv_setuv_mg(SV *sv, UV u)

sv_true
  Returns true if the SV has a true value by Perl's rules.

      	I32	sv_true(SV *sv)

sv_unmagic
  Removes magic from an SV.

      	int	sv_unmagic(SV* sv, int type)

sv_unref
  Unsets the RV status of the SV, and decrements the reference count of whatever was being referenced by the RV. This can almost be thought of as a reversal of `newSVrv`. See `SvROK_off`.

      	void	sv_unref(SV* sv)

sv_upgrade
  Upgrade an SV to a more complex form. Use `SvUPGRADE`. See `svtype`.

      	bool	sv_upgrade(SV* sv, U32 mt)

sv_usepvn
  Tells an SV to use `ptr` to find its string value. Normally the string is stored inside the SV but sv_usepvn allows the SV to use an outside string. The `ptr` should point to memory that was allocated by `malloc`. The string length, `len`, must be supplied. This function will realloc the memory pointed to by `ptr`, so that pointer should not be freed or used by the programmer after giving it to sv_usepvn. Does not handle 'set' magic. See `sv_usepvn_mg`.

      	void	sv_usepvn(SV* sv, char* ptr, STRLEN len)

sv_usepvn_mg
  Like `sv_usepvn`, but also handles 'set' magic.

      	void	sv_usepvn_mg(SV *sv, char *ptr, STRLEN len)

sv_utf8_downgrade
  Attempt to convert the PV of an SV from UTF8-encoded to byte encoding. This may not be possible if the PV contains non-byte encoding characters; if this is the case, either returns false or, if `fail_ok` is not true, croaks.

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

      	bool	sv_utf8_downgrade(SV *sv, bool fail_ok)

sv_utf8_encode
  Convert the PV of an SV to UTF8-encoded, but then turn off the `SvUTF8` flag so that it looks like bytes again. Nothing calls this.

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

      	void	sv_utf8_encode(SV *sv)

sv_utf8_upgrade
  Convert the PV of an SV to its UTF8-encoded form.

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

      	void	sv_utf8_upgrade(SV *sv)

sv_vcatpvfn
  Processes its arguments like `vsprintf` and appends the formatted output to an SV. Uses an array of SVs if the C style variable argument list is missing (NULL). When running with taint checks enabled, indicates via `maybe_tainted` if results are untrustworthy (often due to the use of locales).

      	void	sv_vcatpvfn(SV* sv, const char* pat, STRLEN patlen, va_list* args, SV** svargs, I32 svmax, bool *maybe_tainted)

sv_vsetpvfn
  Works like `vcatpvfn` but copies the text into the SV instead of appending it.

      	void	sv_vsetpvfn(SV* sv, const char* pat, STRLEN patlen, va_list* args, SV** svargs, I32 svmax, bool *maybe_tainted)

THIS
  Variable which is setup by `xsubpp` to designate the object in a C++ XSUB. This is always the proper type for the C++ object. See `CLASS` and the section on Using XS With C++ in the perlxs manpage.

      	(whatever)	THIS

toLOWER
  Converts the specified character to lowercase.

      	char	toLOWER(char ch)

toUPPER
  Converts the specified character to uppercase.

      	char	toUPPER(char ch)

utf8_distance
  Returns the number of UTF8 characters between the UTF-8 pointers `a` and `b`.

  WARNING: use only if you *know* that the pointers point inside the same UTF-8 buffer.

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

      	IV	utf8_distance(U8 *a, U8 *b)

utf8_hop
  Return the UTF-8 pointer `s` displaced by `off` characters, either forward or backward.

  WARNING: do not use the following unless you *know* `off` is within the UTF-8 data pointed to by `s` *and* that on entry `s` is aligned on the first byte of character or just after the last byte of a character.

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

      	U8*	utf8_hop(U8 *s, I32 off)

utf8_length
  Return the length of the UTF-8 char encoded string `s` in characters. Stops at `e` (inclusive). If `e < s` or if the scan would end up past `e`, croaks.

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

      	STRLEN	utf8_length(U8* s, U8 *e)

utf8_to_bytes
  Converts a string `s` of length `len` from UTF8 into byte encoding. Unlike `bytes_to_utf8`, this over-writes the original string, and updates len to contain the new length. Returns zero on failure, setting `len` to -1.

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

      	U8*	utf8_to_bytes(U8 *s, STRLEN *len)

utf8_to_uv
  Returns the character value of the first character in the string `s` which is assumed to be in UTF8 encoding and no longer than `curlen`; `retlen` will be set to the length, in bytes, of that character.

  If `s` does not point to a well-formed UTF8 character, the behaviour is dependent on the value of `flags`: if it contains UTF8_CHECK_ONLY, it is assumed that the caller will raise a warning, and this function will silently just set `retlen` to `-1` and return zero. If the `flags` does not contain UTF8_CHECK_ONLY, warnings about malformations will be given, `retlen` will be set to the expected length of the UTF-8 character in bytes, and zero will be returned.

  The `flags` can also contain various flags to allow deviations from the strict UTF-8 encoding (see `utf8.h`).

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

      	UV	utf8_to_uv(U8 *s, STRLEN curlen, STRLEN* retlen, U32 flags)

utf8_to_uv_simple
  Returns the character value of the first character in the string `s` which is assumed to be in UTF8 encoding; `retlen` will be set to the length, in bytes, of that character.

  If `s` does not point to a well-formed UTF8 character, zero is returned and retlen is set, if possible, to -1.

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

      	UV	utf8_to_uv_simple(U8 *s, STRLEN* retlen)

uv_to_utf8
  Adds the UTF8 representation of the Unicode codepoint `uv` to the end of the string `d`; `d` should be have at least `UTF8_MAXLEN+1` free bytes available. The return value is the pointer to the byte after the end of the new character. In other words,

          d = uv_to_utf8(d, uv);

      is the recommended Unicode-aware way of saying

          *(d++) = uv;

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

      	U8*	uv_to_utf8(U8 *d, UV uv)

warn
  This is the XSUB-writer's interface to Perl's `warn` function. Use this function the same way you use the C `printf` function. See `croak`.

      	void	warn(const char* pat, ...)

XPUSHi
  Push an integer onto the stack, extending the stack if necessary. Handles 'set' magic. See `PUSHi`.

      	void	XPUSHi(IV iv)

XPUSHn
  Push a double onto the stack, extending the stack if necessary. Handles 'set' magic. See `PUSHn`.

      	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. See `PUSHp`.

      	void	XPUSHp(char* str, STRLEN len)

XPUSHs
  Push an SV onto the stack, extending the stack if necessary. Does not handle 'set' magic. See `PUSHs`.

      	void	XPUSHs(SV* sv)

XPUSHu
  Push an unsigned integer onto the stack, extending the stack if necessary. See `PUSHu`.

      	void	XPUSHu(UV uv)

XS
  Macro to declare an XSUB and its C parameter list. This is handled by `xsubpp`.
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 an 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_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)

XS_VERSION
  The version identifier for an XS module. This is usually handled automatically by `ExtUtils::MakeMaker`. See `XS_VERSION_BOOTCHECK`.
XS_VERSION_BOOTCHECK
  Macro to verify that a PM module's $VERSION variable matches the XS module's `XS_VERSION` variable. This is usually handled automatically by `xsubpp`. See the section on The VERSIONCHECK: Keyword in the perlxs manpage.

      		XS_VERSION_BOOTCHECK;

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)

## AUTHORS

Until May 1997, this document was maintained by Jeff Okamoto <okamoto@corp.hp.com>. It is now maintained as part of Perl itself.

With lots of help and suggestions from Dean Roehrich, Malcolm Beattie, Andreas Koenig, Paul Hudson, Ilya Zakharevich, Paul Marquess, Neil Bowers, Matthew Green, Tim Bunce, Spider Boardman, Ulrich Pfeifer, Stephen McCamant, and Gurusamy Sarathy.

API Listing originally by Dean Roehrich <roehrich@cray.com>.

Updated to be autogenerated from comments in the source by Benjamin Stuhl.

## SEE ALSO

perlguts(1), perlxs(1), perlxstut(1), perlintern(1)

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