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
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 may 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, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 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