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 a NULL pointer, the wcstombs function converts the wide-
character string src to a multibyte string starting at dest. At most n
bytes are written to dest. The conversion starts in the initial 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 lost.
3. The wide-character string has been completely converted, including
the terminating L'\0'. In this case the conversion ends in the initial
state. The number of bytes written to dest, excluding the terminating
'\0' byte, is returned.
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 that
no length limit exists.
In order to avoid the case 2 above, the programmer should make sure n
is greater or equal to wcstombs(NULL,src,0)+1.
The wcstombs function returns the number of bytes that make up the con-
verted part of 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.
ISO/ANSI C, UNIX98
The behaviour of wcstombs depends on the LC_CTYPE category of the cur-
The function wcsrtombs provides a thread safe interface to the same
GNU 1999-07-25 WCSTOMBS(3)