converts a multibyte character string
to a wide-character string
* restrict pwcs, const
char * restrict s, size_t
converts a null-terminated multibyte character string pointed to by
s to the corresponding wide-character string and
stores up to n wide characters in the array pointed to
by pwcs. Each character will be converted as if
mbtowc(3) is continuously called, except the internal state of
mbtowc(3) will not be affected.
For state-dependent encoding,
implies the multibyte character string pointed to by s
always begin with an initial state.
These are the special cases:
- pwcs == NULL
mbstowcs() returns the number of elements to store the whole wide-character string corresponding to the multibyte character string pointed to by s. In this case, n is ignored.
- s == NULL
- Undefined (may cause the program to crash).
- 0 or positive
- The value returned is the number of elements stored in the array pointed to by pwcs, except for a terminating null wide character (if any). If pwcs is not null and the value returned is equal to n, the wide-character string pointed to by pwcs is not null terminated. If pwcs is a null pointer, the value returned is the number of elements to contain the whole string converted, except for a terminating null wide character.
- The array indirectly pointed to by s contains a byte
sequence forming invalid character. In this case,
mbstowcs() sets errno to indicate the error.
mbstowcs() may cause an error in the
- s points to the string containing invalid or incomplete multibyte character.
mbstowcs() function conforms to
ANSI X3.159-1989 (“ANSI C89”).
The restrict qualifier is added at ISO/IEC 9899/199 (“ISO