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Name

mbtowc - convert a multibyte sequence to a wide character

Synopsis


#include <stdlib.h>
int mbtowc (wchar_t* pwc, const char* s, size_t n);

Description

The main case for this function is when s is not NULL and pwc is not NULL. In this case, the mbtowc function inspects at most n bytes of the multibyte string starting at s, extracts the next complete multibyte character, converts it to a wide character and stores it at *pwc. It updates an internal shift state only known to the mbtowc function. It s does not point to a '\0' byte, it returns the number of bytes that were consumed from s, otherwise it returns 0.

If the n bytes starting at s do not contain a complete multibyte character, or if they contain an invalid multibyte sequence, mbtowc returns -1. This can happen even if n >= MB_CUR_MAX, if the multibyte string contains redundant shift sequences.

A different case is when s is not NULL but pwc is NULL. In this case the mbtowc function behaves as above, excepts that it does not store the converted wide character in memory.

A third case is when s is NULL. In this case, pwc and n are ignored. The mbtowc function resets the shift state, only known to this function, to the initial state, and returns non-zero if the encoding has non-trivial shift state, or zero if the encoding is stateless.

Return Value

If s is not NULL, the mbtowc function returns the number of consumed bytes starting at s, or 0 if s points to a null byte, or -1 upon failure.

If s is NULL, the mbtowc function returns non-zero if the encoding has non-trivial shift state, or zero if the encoding is stateless.

Conforming to

ISO/ANSI C, UNIX98

See Also

mbrtowc(3) , mbstowcs(3) , MB_CUR_MAX(3)

Notes

The behaviour of mbtowc depends on the LC_CTYPE category of the current locale.

This function is not multi-thread safe. The function mbrtowc provides a better interface to the same functionality.

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