NAME

       mbstowcs - convert a multibyte string to a wide-character string

SYNOPSIS

       #include <stdlib.h>

       size_t mbstowcs(wchar_t *dest, const char *src, size_t n);

DESCRIPTION

       If  dest  is not a NULL pointer, the mbstowcs() function converts the multibyte string src
       to a wide-character string starting at dest.  At most n wide  characters  are  written  to
       dest.   The  conversion  starts  in  the initial state.  The conversion can stop for three
       reasons:

       1. An invalid multibyte sequence has  been  encountered.   In  this  case  (size_t) -1  is
          returned.

       2. n  non-L'\0' wide characters have been stored at dest.  In this case the number of wide
          characters written to dest is returned, but the shift state at this point is lost.

       3. The multibyte string has been completely converted, including the terminating null wide
          character  ('\0').   In  this  case  the  number  of  wide  characters written to dest,
          excluding the terminating null wide character, is returned.

       The programmer must ensure that there is room for at least n wide characters at dest.

       If dest is NULL, n is ignored, and the conversion  proceeds  as  above,  except  that  the
       converted wide characters are not written out to memory, and that no length limit exists.

       In  order to avoid the case 2 above, the programmer should make sure n is greater or equal
       to mbstowcs(NULL,src,0)+1.

RETURN VALUE

       The mbstowcs() function returns the number of wide characters that make up  the  converted
       part  of the wide-character string, not including the terminating null wide character.  If
       an invalid multibyte sequence was encountered, (size_t) -1 is returned.

CONFORMING TO

       C99.

NOTES

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

       The function mbsrtowcs(3) provides a better interface to the same functionality.

SEE ALSO

       mbsrtowcs(3), wcstombs(3)

COLOPHON

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