mbtowc, _mbtowc_l

Convert a multibyte character to a corresponding wide character.

Syntax

int mbtowc(
   wchar_t *wchar,
   const char *mbchar,
   size_t count
);
int _mbtowc_l(
   wchar_t *wchar,
   const char *mbchar,
   size_t count,
   _locale_t locale
);

Parameters

wchar
Address of a wide character (type wchar_t).

mbchar
Address of a sequence of bytes (a multibyte character).

count
Number of bytes to check.

locale
The locale to use.

Return value

If mbchar isn't NULL, and if mbchar points to a valid multibyte character, mbtowc returns the length in bytes of the multibyte character. If mbchar is NULL or points to a wide-character null character (L'\0'), the function returns 0. If the object that mbchar points to doesn't form a valid multibyte character within the first count characters, it returns -1.

Remarks

The mbtowc function converts count or fewer bytes pointed to by mbchar, if mbchar isn't NULL, to a corresponding wide character. mbtowc stores the resulting wide character at wchar, if wchar isn't NULL. mbtowc doesn't examine more than MB_CUR_MAX bytes. mbtowc uses the current locale for locale-dependent behavior; _mbtowc_l is identical except that it uses the locale passed in instead. For more information, see Locale.

By default, this function's global state is scoped to the application. To change this behavior, see Global state in the CRT.

Requirements

Routine	Required header
mbtowc	<stdlib.h>
_mbtowc_l	<stdlib.h>

For more compatibility information, see Compatibility.

Libraries

All versions of the C run-time libraries.

Example

// crt_mbtowc.c
// Illustrates the behavior of the mbtowc function

#include <stdlib.h>
#include <stdio.h>

int main( void )
{
    int      i;
    char    *pmbc    = (char *)malloc( sizeof( char ) );
    wchar_t  wc      = L'a';
    wchar_t *pwcnull = NULL;
    wchar_t *pwc     = (wchar_t *)malloc( sizeof( wchar_t ) );
    printf( "Convert a wide character to multibyte character:\n" );
    wctomb_s( &i, pmbc, sizeof(char), wc );
    printf( "  Characters converted: %u\n", i );
    printf( "  Multibyte character: %x\n\n", *pmbc );

    printf( "Convert multibyte character back to a wide "
            "character:\n" );
    i = mbtowc( pwc, pmbc, MB_CUR_MAX );
    printf( "   Bytes converted: %u\n", i );
    printf( "   Wide character: %x\n\n", *pwc );
    printf( "Attempt to convert when target is NULL\n" );
    printf( "   returns the length of the multibyte character:\n" );
    i = mbtowc( pwcnull, pmbc, MB_CUR_MAX );
    printf( "   Length of multibyte character: %u\n\n", i );

    printf( "Attempt to convert a NULL pointer to a" );
    printf( " wide character:\n" );
    pmbc = NULL;
    i = mbtowc( pwc, pmbc, MB_CUR_MAX );
    printf( "   Bytes converted: %u\n", i );
}

Convert a wide character to multibyte character:
   Characters converted: 1
   Multibyte character: 61

Convert multibyte character back to a wide character:
   Bytes converted: 1
   Wide character: 61

Attempt to convert when target is NULL
   returns the length of the multibyte character:
   Length of multibyte character: 1

Attempt to convert a NULL pointer to a wide character:
   Bytes converted: 0

See also

Data conversion
MultiByteToWideChar
Locale
Interpretation of multibyte-character sequences
_mbclen, mblen, _mblen_l
wcstombs, _wcstombs_l
wctomb, _wctomb_l