Namespaces
Variants
Views
Actions

wctomb

From cppreference.com
< c‎ | string‎ | multibyte
Revision as of 13:03, 4 February 2014 by P12 (Talk | contribs)

(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Defined in header <stdlib.h>
int wctomb( char* s, wchar_t wc );

Converts a wide character wc to multibyte encoding and stores it (including any shift sequences) in the char array whose first element is pointed to by s. No more than MB_CUR_MAX characters are stored.

If wc is the null character, the null byte is written to s, preceded by any shift sequences necessary to restore the initial shift state.

If s is a null pointer, resets the global conversion state and determines whether shift sequences are used.

Contents

[edit] Notes

Each call to wctomb updates the internal global conversion state (a static object of type mbstate_t, only known to this function). If the multibyte encoding uses shift states, this function is not reentrant. In any case, multiple threads should not call wctomb without synchronization: wcrtomb may be used instead.

[edit] Parameters

s - pointer to the character array for output
wc - wide character to convert

[edit] Return value

If s is not a null pointer, returns the number of bytes that are contained in the multibyte representation of wc or -1 if wc is not a valid character.

If s is a null pointer, resets its internal conversion state to represent the initial shift state and returns 0 if the current multibyte encoding is not state-dependent (does not use shift sequences) or a non-zero value if the current multibyte encoding is state-dependent (uses shift sequences).

[edit] Example

#include <stdio.h>
#include <stdlib.h>
#include <locale.h>
 
void demo(wchar_t wc)
{
    printf("State-dependent encoding?   %d\n", wctomb(NULL, wc));
 
    char mb[MB_CUR_MAX];
    int len = wctomb(mb,wc);
    printf("wide char '%lc' -> multibyte char '", wc);
    for (int idx = 0; idx < len; ++idx)
        printf("%#2x ", (unsigned char)mb[idx]);
    printf("'\n");
}
 
int main () 
{
    setlocale(LC_ALL, "en_US.utf8");
    printf("MB_CUR_MAX = %zu\n", MB_CUR_MAX);
    demo(L'A');
    demo(L'\u00df');
    demo(L'\U0001d10b');
}

Output:

MB_CUR_MAX = 6
State-dependent encoding?   0
wide char 'A' -> multibyte char '0x41 '
State-dependent encoding?   0
wide char 'ß' -> multibyte char '0xc3 0x9f '
State-dependent encoding?   0
wide char '𝄋' -> multibyte char '0xf0 0x9d 0x84 0x8b '

[edit] See also

converts the next multibyte character to wide character
(function) [edit]
converts a wide character to its multibyte representation, given state
(function) [edit]