mbstowcs — convert a multibyte string to a wide-character string
#include <stdlib.h>
size_t mbstowcs( |
wchar_t * | dest, |
| const char * | src, | |
| size_t | n); |
If dest is not a
NULL pointer, the mbstowcs()
function converts the multibyte string src to a wide-character string
starting at dest. At
most n wide
characters are written to dest. The conversion starts in
the initial state. The conversion can stop for three
reasons:
An invalid multibyte sequence has been encountered. In this case (size_t) −1 is returned.
n non-L'\0'
wide characters have been stored at dest. In this case the
number of wide characters written to dest is returned, but the
shift state at this point is lost.
The multibyte string has been completely converted,
including the terminating '\0'. In this case the number
of wide characters written to dest, excluding the
terminating L'\0' character, is returned.
The programmer must ensure that there is room for at least
n wide characters at
dest.
If dest is NULL,
n is ignored, and the
conversion proceeds as above, except that the converted wide
characters 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 mbstowcs(NULL,src,0)+1.
The mbstowcs() function
returns the number of wide characters that make up the
converted part of the wide-character string, not including
the terminating null wide character. If an invalid multibyte
sequence was encountered, (size_t)
−1 is returned.
The behavior of mbstowcs()
depends on the LC_CTYPE
category of the current locale.
The function mbsrtowcs(3) provides a better interface to the same functionality.