WCSTOMBS(3) Linux Programmer's Manual WCSTOMBS(3)
wcstombs - convert a wide-character string to a multibyte string
size_t wcstombs(char *dest, const wchar_t *src, size_t n);
If dest is not NULL, the wcstombs() function converts the wide-charac-
ter string src to a multibyte string starting at dest. At most n bytes
are written to dest. The sequence of characters placed in dest begins
in the initial shift state. The conversion can stop for three reasons:
1. A wide character has been encountered that can not be represented as
a multibyte sequence (according to the current locale). In this
case, (size_t) -1 is returned.
2. The length limit forces a stop. In this case, the number of bytes
written to dest is returned, but the shift state at this point is
3. The wide-character string has been completely converted, including
the terminating null wide character (L'\0'). In this case, the con-
version ends in the initial shift state. The number of bytes writ-
ten to dest, excluding the terminating null byte ('\0'), is
The programmer must ensure that there is room for at least n bytes at
If dest is NULL, n is ignored, and the conversion proceeds as above,
except that the converted bytes are not written out to memory, and no
length limit exists.
In order to avoid the case 2 above, the programmer should make sure n
is greater than or equal to wcstombs(NULL,src,0)+1.
The wcstombs() function returns the number of bytes that make up the
converted part of a multibyte sequence, not including the terminating
null byte. If a wide character was encountered which could not be con-
verted, (size_t) -1 is returned.
For an explanation of the terms used in this section, see
|Interface | Attribute | Value |
|wcstombs() | Thread safety | MT-Safe |
POSIX.1-2001, POSIX.1-2008, C99.
The behavior of wcstombs() depends on the LC_CTYPE category of the cur-
The function wcsrtombs(3) provides a better interface to the same func-
mblen(3), mbstowcs(3), mbtowc(3), wcsrtombs(3) wctomb(3)
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