wctomb, wctomb_s

 

C

Language

headers

Type support

Dynamic memory management

Error handling

Program utilities

Variadic function support

Date and time utilities

Strings library

Algorithms

Numerics

Input/output support

Localization support

Thread support (C11)

Atomic operations (C11)

Technical Specifications

 

Strings library

Byte strings

Multibyte strings

Wide strings

 

Null-terminated multibyte strings

Wide/multibyte conversions
mbsinit (C95)
mbtowc mbstowcsmbstowcs_s (C11) btowc (C95) mbrtowc (C95) mbsrtowcsmbsrtowcs_s (C95)(C11) mbrtoc16 (C11) c16rtomb (C11) c32rtomb (C11) mbrtoc32 (C11)	mblen wctombwctomb_s (C11) wcstombswcstombs_s (C11) wctob (C95) wcrtombwcrtomb_s (C95)(C11) wcsrtombswcsrtombs_s (C95)(C11) mbrlen (C95)
Types
mbstate_t (C95)

 

Defined in header <stdlib.h>
int wctomb( char *s, wchar_t wc );	(1)
errno_t wctomb_s(int *restrict status, char *restrict s, rsize_t ssz, wchar_t wc);	(2)	(since C11)

1) Converts a wide character wc to multibyte encoding and stores it (including any shift sequences) in the char array whose first element is pointed to by s. No more than MB_CUR_MAX characters are stored.

If wc is the null character, the null byte is written to s, preceded by any shift sequences necessary to restore the initial shift state.

If s is a null pointer, this function resets the global conversion state and determines whether shift sequences are used.

2) Same as (1), except that the result is returned in the out-parameter status and the following errors are detected at runtime and call the currently installed constraint handler function:

• ssz is less than the number of bytes that would be written (unless s is null)
• ssz is greater than RSIZE_MAX (unless s is null)
• s is a null pointer but ssz is not zero

As all bounds-checked functions, wctomb_s is only guaranteed to be available if __STDC_LIB_EXT1__ is defined by the implementation and if the user defines __STDC_WANT_LIB_EXT1__ to the integer constant 1 before including stdlib.h.

Notes

Each call to wctomb updates the internal global conversion state (a static object of type mbstate_t, only known to this function). If the multibyte encoding uses shift states, this function is not reentrant. In any case, multiple threads should not call wctomb without synchronization: wcrtomb or wctomb_s may be used instead.

Unlike most bounds-checked functions, wctomb_s does not null-terminate its output, because it is designed to be used in loops that process strings character-by-character.

Parameters

s	-	pointer to the character array for output
wc	-	wide character to convert
ssz	-	maximum number of bytes to write to s (size of the array s)
status	-	pointer to an out-parameter where the result (length of the multibyte sequence or the shift sequence status) will be stored

Return value

1) If s is not a null pointer, returns the number of bytes that are contained in the multibyte representation of wc or -1 if wc is not a valid character.

If s is a null pointer, resets its internal conversion state to represent the initial shift state and returns ​0​ if the current multibyte encoding is not state-dependent (does not use shift sequences) or a non-zero value if the current multibyte encoding is state-dependent (uses shift sequences).

2) zero on success, in which case the multibyte representation of wc is stored in s and its length is stored in *status, or, if s is null, the shift sequence status is stored in status). Non-zero on encoding error or runtime constraint violation, in which case (size_t)-1 is stored in *status. The value stored in *status never exceeds MB_CUR_MAX