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mbtowc(3) [netbsd man page]

MBTOWC(3)						   BSD Library Functions Manual 						 MBTOWC(3)

mbtowc -- converts a multibyte character to a wide character LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <stdlib.h> int mbtowc(wchar_t * restrict pwc, const char * restrict s, size_t n); DESCRIPTION
mbtowc() usually converts the multibyte character pointed to by s to a wide character, and stores it in the wchar_t object pointed to by pwc if pwc is non-NULL and s points to a valid character. This function may inspect at most n bytes of the array beginning from s. In state-dependent encodings, s may point to the special sequence bytes to change the shift-state. Although such sequence bytes correspond to no individual wide-character code, mbtowc() changes its own state by the sequence bytes and treats them as if they are a part of the sub- sequence multibyte character. Unlike mbrtowc(3), the first n bytes pointed to by s need to form an entire multibyte character. Otherwise, this function causes an error. Calling any other functions in Standard C Library (libc, -lc) never changes the internal state of mbtowc(), except for calling setlocale(3) with changing the LC_CTYPE category of the current locale. Such setlocale(3) call causes the internal state of this function to be indeter- minate. The behaviour of mbtowc() is affected by the LC_CTYPE category of the current locale. There are special cases: s == NULL mbtowc() initializes its own internal state to an initial state, and determines whether the current encoding is state-depen- dent. This function returns 0 if the encoding is state-independent, otherwise non-zero. In this case, pwc is completely ignored. pwc == NULL mbtowc() executes the conversion as if pwc is non-NULL, but a result of the conversion is discarded. n == 0 In this case, the first n bytes of the array pointed to by s never form a complete character. Thus, the mbtowc() always fails. RETURN VALUES
Normally, the mbtowc() returns: 0 s points to a nul byte (''). positive Number of bytes for the valid multibyte character pointed to by s. There are no cases that the value returned is greater than the value of the MB_CUR_MAX macro. -1 s points to an invalid or an incomplete multibyte character. The mbtowc() also sets errno to indicate the error. When s is equal to NULL, mbtowc() returns: 0 The current encoding is state-independent. non-zero The current encoding is state-dependent. ERRORS
mbtowc() may cause an error in the following case: [EILSEQ] s points to an invalid or incomplete multibyte character. SEE ALSO
mblen(3), mbrtowc(3), setlocale(3) STANDARDS
The mbtowc() function conforms to ANSI X3.159-1989 (``ANSI C89''). The restrict qualifier is added at ISO/IEC 9899:1999 (``ISO C99''). BSD
February 3, 2002 BSD

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MBTOWC(3)						     Linux Programmer's Manual							 MBTOWC(3)

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 known only to the mbtowc() function. If s does not point to a null 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, except 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 nonzero if the encoding has nontrivial 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 nonzero if the encoding has nontrivial shift state, or zero if the encoding is stateless. ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7). +----------+---------------+----------------+ |Interface | Attribute | Value | +----------+---------------+----------------+ |mbtowc() | Thread safety | MT-Unsafe race | +----------+---------------+----------------+ CONFORMING TO
POSIX.1-2001, POSIX.1-2008, C99. NOTES
The behavior of mbtowc() depends on the LC_CTYPE category of the current locale. This function is not multithread safe. The function mbrtowc(3) provides a better interface to the same functionality. SEE ALSO
MB_CUR_MAX(3), mblen(3), mbrtowc(3), mbstowcs(3), wcstombs(3), wctomb(3) COLOPHON
This page is part of release 4.15 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at GNU
2016-10-08 MBTOWC(3)
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