This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
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.1‐2008 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.
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.
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) 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.unix.org/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
IEEE/The Open Group 2013 MBSTOWCS(3P)