Wide-character type and utilities

Names specified here
Name	Description	Notes				Source
`__STDC_ISO_10646__`	Unicode version	L	?	M		Predefined	C99	C11
`ATOMIC_WCHAR_T_LOCK_FREE`	Lock-free property of type `atomic_wchar_t`		?	M		`<stdatomic.h>`		C11
`atomic_wchar_t`	Atomic character type		?		T	`<stdatomic.h>`		C11

Names specified for `<wchar.h>`, “Wide-character type and utilities”
Name	Description	Notes				Source	Availability
`btowc()`	Convert multibyte character to wide character				(·)	`<wchar.h>`			C95	C99	C11
`errno_t`	Error-number type		?		T	Headers					C11
`fgetwc()`	Input wide character				(·)	`<wchar.h>`			C95	C99	C11
`fgetws()`	Input line of wide characters				(·)	`<wchar.h>`			C95	C99	C11
`fputwc()`	Output wide character				(·)	`<wchar.h>`			C95	C99	C11
`fputws()`	Output line of wide characters				(·)	`<wchar.h>`			C95	C99	C11
`fwide()`	Set/determine stream width				(·)	`<wchar.h>`			C95	C99	C11
`fwprintf()`	Print formatted text				(·)	`<wchar.h>`			C95	C99	C11
`fwprintf_s()`	Print formatted text		?		(·)	`<wchar.h>`					C11
`fwscanf()`	Input formatted text				(·)	`<wchar.h>`			C95	C99	C11
`fwscanf_s()`	Input formatted text		?		(·)	`<wchar.h>`					C11
`getwc()`	Input wide character				(·)	`<wchar.h>`			C95	C99	C11
`getwchar()`	Input wide character from standard input				(·)	`<wchar.h>`			C95	C99	C11
`mbrlen()`	Compute multibyte character length				(·)	`<wchar.h>`			C95	C99	C11
`mbrtowc()`	Convert multibyte character to wide character				(·)	`<wchar.h>`			C95	C99	C11
`mbsinit()`	Test for initial state				(·)	`<wchar.h>`			C95	C99	C11
`mbsrtowcs()`	Convert multibyte string to wide string				(·)	`<wchar.h>`			C95	C99	C11
`mbsrtowcs_s()`	Convert multibyte string to wide string				(·)	`<wchar.h>`					C11
`mbstate_t`	Multibyte conversion state				T	Headers			C95	C99	C11
`NULL`	Null pointer constant	L		M		Headers	C89	C90	C95	C99	C11
`putwc()`	Output wide character				(·)	`<wchar.h>`			C95	C99	C11
`putwchar()`	Output wide character to standard output				(·)	`<wchar.h>`			C95	C99	C11
`rsize_t`	Implementation-defined size type with implied run-time constraints	L	?		T	Headers					C11
`size_t`	Implementation-defined size type	H			T	Headers	C89	C90	C95	C99	C11
`snwprintf_s()`	Print formatted text		?		(·)	`<wchar.h>`					C11
`struct tm`	Time type				T	Headers	C89	C90	C95	C99	C11
`swprintf()`	Print formatted text				(·)	`<wchar.h>`			C95	C99	C11
`swprintf_s()`	Print formatted text		?		(·)	`<wchar.h>`					C11
`swscanf()`	Input formatted text				(·)	`<wchar.h>`			C95	C99	C11
`swscanf_s()`	Input formatted text		?		(·)	`<wchar.h>`					C11
`ungetwc()`	Replace character				(·)	`<wchar.h>`			C95	C99	C11
`vfwprintf()`	Print formatted text				(·)	`<wchar.h>`			C95	C99	C11
`vfwprintf_s()`	Print formatted text		?		(·)	`<wchar.h>`					C11
`vfwscanf()`	Input formatted text				(·)	`<wchar.h>`			C95	C99	C11
`vfwscanf_s()`	Input formatted text		?		(·)	`<wchar.h>`					C11
`vsnwprintf_s()`	Print formatted text		?		(·)	`<wchar.h>`					C11
`vswprintf()`	Print formatted text				(·)	`<wchar.h>`			C95	C99	C11
`vswprintf_s()`	Print formatted text		?		(·)	`<wchar.h>`					C11
`vswscanf()`	Input formatted text				(·)	`<wchar.h>`				C99	C11
`vswscanf_s()`	Input formatted text		?		(·)	`<wchar.h>`					C11
`vwprintf()`	Print formatted text				(·)	`<wchar.h>`			C95	C99	C11
`vwprintf_s()`	Print formatted text		?		(·)	`<wchar.h>`					C11
`vwscanf()`	Input formatted text				(·)	`<wchar.h>`				C99	C11
`vwscanf_s()`	Input formatted text		?		(·)	`<wchar.h>`					C11
`WCHAR_MAX`	Maximum value of `wchar_t`	H		M		Headers			C95	C99	C11
`WCHAR_MIN`	Minimum value of `wchar_t`	H		M		Headers			C95	C99	C11
`WEOF`	End-of-stream indicator	H		M		Headers			C95	C99	C11
`wchar_t`	Wide-character type	H			T	Headers			C95	C99	C11
`wcrtomb()`	Convert wide character to multibyte character				(·)	`<wchar.h>`			C95	C99	C11
`wcrtomb_s()`	Convert wide character to multibyte character		?		(·)	`<wchar.h>`					C11
`wcscat()`	Catenate wide-character strings				(·)	`<wchar.h>`			C95	C99	C11
`wcscat_s()`	Catenate wide-character strings		?		(·)	`<wchar.h>`					C11
`wcschr()`	Search wide-character string for first occurance of character				(·)	`<wchar.h>`			C95	C99	C11
`wcscmp()`	Compare wide-character string				(·)	`<wchar.h>`			C95	C99	C11
`wcscoll()`	Compare wide-character string				(·)	`<wchar.h>`			C95	C99	C11
`wcscpy()`	Copy wide-character string				(·)	`<wchar.h>`			C95	C99	C11
`wcscpy_s()`	Copy wide-character string		?		(·)	`<wchar.h>`					C11
`wcscspn()`	Search wide-character string for longest span of complement of set of characters				(·)	`<wchar.h>`			C95	C99	C11
`wcsftime()`	Convert time to string				(·)	`<wchar.h>`			C95	C99	C11
`wcslen()`	Compute length of wide-character string				(·)	`<wchar.h>`			C95	C99	C11
`wcsncat()`	Catenate wide-character strings				(·)	`<wchar.h>`			C95	C99	C11
`wcsncat_s()`	Catenate wide-character strings		?		(·)	`<wchar.h>`					C11
`wcsncmp()`	Compare wide-character string				(·)	`<wchar.h>`			C95	C99	C11
`wcsncpy()`	Copy wide-character string				(·)	`<wchar.h>`			C95	C99	C11
`wcsncpy_s()`	Copy wide-character string		?		(·)	`<wchar.h>`					C11
`wcsnlen_s()`	Compute length of wide-character string		?		(·)	`<wchar.h>`					C11
`wcspbrk()`	Search wide-character string for first of set of characters				(·)	`<wchar.h>`			C95	C99	C11
`wcsrchr()`	Search wide-character string for last occurance of character				(·)	`<wchar.h>`			C95	C99	C11
`wcsrtombs()`	Convert wide string to multibyte string				(·)	`<wchar.h>`			C95	C99	C11
`wcsrtombs_s()`	Convert wide string to multibyte string		?		(·)	`<wchar.h>`					C11
`wcsspn()`	Search wide-character string for longest span of set of characters				(·)	`<wchar.h>`			C95	C99	C11
`wcsstr()`	Search wide-character string for string				(·)	`<wchar.h>`			C95	C99	C11
`wcstod()`	Convert wide-character string to real				(·)	`<wchar.h>`			C95	C99	C11
`wcstof()`	Convert wide-character string to real				(·)	`<wchar.h>`				C99	C11
`wcstok()`	Tokenize wide-character string				(·)	`<wchar.h>`			C95	C99	C11
`wcstok_s()`	Tokenize wide-character string		?		(·)	`<wchar.h>`					C11
`wcstol()`	Convert wide-character string to integer				(·)	`<wchar.h>`			C95	C99	C11
`wcstold()`	Convert wide-character string to real				(·)	`<wchar.h>`				C99	C11
`wcstoll()`	Convert wide-character string to integer				(·)	`<wchar.h>`				C99	C11
`wcstoul()`	Convert wide-character string to integer				(·)	`<wchar.h>`			C95	C99	C11
`wcstoull()`	Convert wide-character string to integer				(·)	`<wchar.h>`				C99	C11
`wcsxfrm()`	Transform wide-character string				(·)	`<wchar.h>`			C95	C99	C11
`wctob()`	Convert wide character to multibyte character				(·)	`<wchar.h>`			C95	C99	C11
`wint_t`	Wide-character or error type	H			T	Headers			C95	C99	C11
`wmemchr()`	Search wide-character memory				(·)	`<wchar.h>`			C95	C99	C11
`wmemcmp()`	Compare wide-character memory				(·)	`<wchar.h>`			C95	C99	C11
`wmemcpy()`	Copy wide-character memory				(·)	`<wchar.h>`			C95	C99	C11
`wmemcpy_s()`	Copy wide-character memory		?		(·)	`<wchar.h>`					C11
`wmemmove()`	Copy overlapping wide-character memory				(·)	`<wchar.h>`			C95	C99	C11
`wmemmove_s()`	Copy overlapping wide-character memory		?		(·)	`<wchar.h>`					C11
`wmemset()`	Initialize wide-character memory				(·)	`<wchar.h>`			C95	C99	C11
`wprintf()`	Print formatted text				(·)	`<wchar.h>`			C95	C99	C11
`wprintf_s()`	Print formatted text		?		(·)	`<wchar.h>`					C11
`wscanf()`	Input formatted text				(·)	`<wchar.h>`			C95	C99	C11
`wscanf_s()`	Input formatted text		?		(·)	`<wchar.h>`					C11

This header is available in C95, C99 and C11.

A wide character has type wchar_t, an integer type with the range WCHAR_MIN to WCHAR_MAX. This is usually a bigger range than char, and so wchar_t can obviate multibyte encodings.

If the macro __STDC_ISO_10646__ is defined, the numerical values of wide characters is identical to Unicode. The expansion of the macro is a date of the form yyyymmL, giving the year yyyy and month mm of the version of Unicode supported.

The header <wchar.h> provides several functions involving wide characters, which are analogues of functions in <stdio.h> and <string.h>. <wctype.h> also provides several related functions.

A number of low-level functions are provided to do internal conversion between wide characters amd multibyte characters.

atomic_wchar_t is an alias for _Atomic wchar_t. This type is lock-free always if ATOMIC_WCHAR_T_LOCK_FREE is 2, sometimes if 1, and never if 0.