mbtowc(3) - NetBSD Manual Pages

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MBTOWC(3)               NetBSD Library Functions Manual              MBTOWC(3)

mbtowc -- converts a multibyte character to a wide character
Standard C Library (libc, -lc)
#include <stdlib.h> int mbtowc(wchar_t * restrict pwc, const char * restrict s, size_t n);
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 subsequence 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 inde- terminate. 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-dependent. 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.
Normally, the mbtowc() returns: 0 s points to a nul byte (`\0'). 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 charac- ter. 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.
mbtowc() may cause an error in the following case: [EILSEQ] s points to an invalid or incomplete multibyte charac- ter.
mblen(3), mbrtowc(3), setlocale(3)
The mbtowc() function conforms to ANSI X3.159-1989 (``ANSI C89''). The restrict qualifier is added at ISO/IEC 9899:1999 (``ISO C99''). NetBSD 10.99 February 3, 2002 NetBSD 10.99
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