MBSTOWCS(3)                POSIX Programmer's Manual               MBSTOWCS(3)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

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

SYNOPSIS
       #include <stdlib.h>

       size_t mbstowcs(wchar_t *restrict pwcs, const char *restrict _s,
           size_t _n);

DESCRIPTION
       The functionality described on this reference page is aligned with the
       ISO C standard. Any conflict between the requirements described here
       and the ISO C standard is unintentional. This volume of POSIX.1-2017
       defers to the ISO C standard.

       The mbstowcs() function shall convert a sequence of characters that
       begins in the initial shift state from the array pointed to by _s into a
       sequence of corresponding wide-character codes and shall store not more
       than _n wide-character codes into the array pointed to by pwcs.  No
       characters that follow a null byte (which is converted into a wide-
       character code with value 0) shall be examined or converted. Each
       character shall be converted as if by a call to mbtowc(), except that
       the shift state of mbtowc() is not affected.

       No more than _n elements shall be modified in the array pointed to by
       pwcs.  If copying takes place between objects that overlap, the
       behavior is undefined.

       The behavior of this function shall be affected by the LC__CTYPE
       category of the current locale.  If pwcs is a null pointer, mbstowcs()
       shall return the length required to convert the entire array regardless
       of the value of _n, but no values are stored.

RETURN VALUE
       If an invalid character is encountered, mbstowcs() shall return
       (size_t)-1 and shall set errno to indicate the error.

       Otherwise, mbstowcs() shall return the number of the array elements
       modified (or required if pwcs is null), not including a terminating 0
       code, if any. The array shall not be zero-terminated if the value
       returned is _n.

ERRORS
       The mbstowcs() function shall fail if:

       EILSEQ An invalid character sequence is detected. In the POSIX locale
              an [EILSEQ] error cannot occur since all byte values are valid
              characters.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       mblen(), mbtowc(), wctomb(), wcstombs()

       The Base Definitions volume of POSIX.1-2017, <stdlib.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  In the event of any discrepancy between this version and the
       original IEEE and The Open Group Standard, the original IEEE and The
       Open Group Standard is the referee document. The original Standard can
       be obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2017                          MBSTOWCS(3)
