wctomb

 

C

Language

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Type support

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Program utilities

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Input/output support

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Atomic operations (C11)

 

Strings library

Byte strings

Multibyte strings

Wide strings

 

Null-terminated multibyte strings

Wide/multibyte conversions
mbsinit
mbtowc mbstowcs btowc mbrtowc mbsrtowcs mblen mbrtoc16 c16rtomb	wctomb wcstombs wctob wcrtomb wcsrtombs mbrlen mbrtoc32 c32rtomb
Types
mbstate_t

 

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.

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.

Parameters

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

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).

Example

Run this code

#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 '

See also

mbtowc	converts the next multibyte character to wide character (function)
wcrtomb	converts a wide character to its multibyte representation, given state (function)
C++ documentation for wctomb