NAME

       mbtowc - convert a multibyte sequence to a wide character

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

       #include <stdlib.h>

       int mbtowc(wchar_t *restrict pwc, const char s[restrict .n], 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 ('\0'), 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 │
       └────────────────────────────────────────────────────────┴───────────────┴────────────────┘

VERSIONS

       This  function  is  not  multithread  safe.   The  function  mbrtowc(3)  provides a better
       interface to the same functionality.

STANDARDS

       C11, POSIX.1-2008.

HISTORY

       POSIX.1-2001, C99.

NOTES

       The behavior of mbtowc() depends on the LC_CTYPE category of the current locale.

SEE ALSO

       MB_CUR_MAX(3), mblen(3), mbrtowc(3), mbstowcs(3), wcstombs(3), wctomb(3)