WCSTOMBS(P) POSIX Programmer's Manual WCSTOMBS(P)
wcstombs - convert a wide-character string to a character string
size_t wcstombs(char *restrict s, const wchar_t *restrict pwcs,
The wcstombs() function shall convert the sequence of wide-character codes that are in the
array pointed to by pwcs into a sequence of characters that begins in the initial shift
state and store these characters into the array pointed to by s, stopping if a character
would exceed the limit of n total bytes or if a null byte is stored. Each wide-character
code shall be converted as if by a call to wctomb(), except that the shift state of
wctomb() shall not be affected.
The behavior of this function shall be affected by the LC_CTYPE category of the current
No more than n bytes shall be modified in the array pointed to by s. If copying takes
place between objects that overlap, the behavior is undefined. If s is a null pointer,
wcstombs() shall return the length required to convert the entire array regardless of the
value of n, but no values are stored.
The wcstombs() function need not be reentrant. A function that is not required to be reen-
trant is not required to be thread-safe.
If a wide-character code is encountered that does not correspond to a valid character (of
one or more bytes each), wcstombs() shall return (size_t)-1. Otherwise, wcstombs() shall
return the number of bytes stored in the character array, not including any terminating
null byte. The array shall not be null-terminated if the value returned is n.
The wcstombs() function may fail if:
EILSEQ A wide-character code does not correspond to a valid character.
The following sections are informative.
mblen() , mbtowc() , mbstowcs() , wctomb() , the Base Definitions volume of
IEEE Std 1003.1-2001, <stdlib.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE Std
1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System
Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by
the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and The Open Group
Standard, the original IEEE and The Open Group Standard is the referee document. The orig-
inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 WCSTOMBS(P)