mbtowc---minimal multibyte to wide char converterSynopsis
#include <stdlib.h> int mbtowc(wchar_t *pwc, const char *s, size_t n);
Description
When MB_CAPABLE is not defined, this is a minimal ANSI-conforming
implementation of mbtowc. In this case,
only ``multi-byte character sequences'' recognized are single bytes,
and they are ``converted'' to themselves.
Each call to mbtowc copies one character from *s to
*pwc, unless s is a null pointer. The argument n
is ignored.
When MB_CAPABLE is defined, this routine calls _mbtowc_r to perform
the conversion, passing a state variable to allow state dependent
decoding. The result is based on the locale setting which may
be restricted to a defined set of locales.
Returns
This implementation of mbtowc returns 0 if
s is NULL or is the empty string;
it returns 1 if not MB_CAPABLE or
the character is a single-byte character; it returns -1
if n is 0 or the multi-byte character is invalid;
otherwise it returns the number of bytes in the multibyte character.
If the return value is -1, no changes are made to the pwc
output string. If the input is the empty string, a wchar_t nul
is placed in the output string and 0 is returned. If the input
has a length of 0, no changes are made to the pwc output string.
Portability
mbtowc is required in the ANSI C standard. However, the precise
effects vary with the locale.
mbtowc requires no supporting OS subroutines.
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