Linux manual pages Section 3: Subroutines  

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

This page is part of release 3.52 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man−pages/.


  Copyright (c) Bruno Haible <haibleclisp.cons.org>

%%%LICENSE_START(GPLv2+_DOC_ONEPARA)
This is free documentation; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of
the License, or (at your option) any later version.
%%%LICENSE_END

References consulted:
  GNU glibc-2 source code and manual
  Dinkumware C library reference http://www.dinkumware.com/
  OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
  ISO/IEC 9899:1999