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WCSTOMBS(3) Library Functions Manual WCSTOMBS(3)

wcstombsconverts a wide-character string to a multibyte character string

#include <stdlib.h>

size_t
wcstombs(char * restrict s, const wchar_t * restrict pwcs, size_t n);

wcstombs() converts the null-terminated wide-character string pointed to by pwcs to the corresponding multibyte character string, and stores up to n bytes in the array pointed to by s. Each character will be converted as if wctomb(3) is continuously called, except the internal state of wctomb(3) will not be affected.

For state-dependent encoding, the wcstombs() implies the result multibyte character string pointed to by s always to begin with an initial state.

The behaviour of the wcstombs() is affected by the LC_CTYPE category of the current locale.

There are special cases:

s == NULL
The wcstombs() returns the number of bytes to store the whole multibyte character string corresponding to the wide-character string pointed to by pwcs. In this case, n is ignored.
pwcs == NULL
Undefined (may causes the program to crash).

wcstombs() returns:

0 or positive
Number of bytes stored in the array pointed to by s. There are no cases that the value returned is greater than n (unless s is a null pointer). If the return value is equal to n, the string pointed to by s will not be null-terminated.
(size_t)-1
pwcs points the string containing invalid wide character. wcstombs() also sets errno to indicate the error.

wcstombs() may cause an error in the following cases:

[]
pwcs Points to the string containing invalid wide character.

setlocale(3), wctomb(3)

The wcstombs() function conforms to ANSI X3.159-1989 (“ANSI C89”). The restrict qualifier is added at ISO/IEC 9899/1999 (“ISO C99”).

March 22, 2015 OpenBSD-current