The mbsrtowcs() function shall convert a sequence of characters,
beginning in the conversion state described by the object pointed to by
ps, from the array indirectly pointed to by src into a sequence
of corresponding wide characters. If dst is not a null pointer, the
converted characters shall be stored into the array pointed to by dst.
Conversion continues up to and including a terminating null character, which
shall also be stored. Conversion shall stop early in either of the following
A sequence of bytes is encountered that does not form a
len codes have been stored into the array pointed to
by dst (and dst is not a null pointer).
Each conversion shall take place as if by a call to the mbrtowc()
If dst is not a null pointer, the pointer object pointed to by src
shall be assigned either a null pointer (if conversion stopped due to reaching
a terminating null character) or the address just past the last character
converted (if any). If conversion stopped due to reaching a terminating null
character, and if dst is not a null pointer, the resulting state
described shall be the initial conversion state.
If ps is a null pointer, the mbsrtowcs() function shall use its
own internal mbstate_t object, which is initialized at program start-up
to the initial conversion state. Otherwise, the mbstate_t object
pointed to by ps shall be used to completely describe the current
conversion state of the associated character sequence. The implementation
behaves as if no function defined in this volume of
IEEE Std 1003.1-2001 calls mbsrtowcs().
The behavior of this function shall be affected by the LC_CTYPE category
of the current locale.
If the input conversion encounters a sequence of bytes that do not form a valid
character, an encoding error occurs. In this case, the mbsrtowcs()
function stores the value of the macro [EILSEQ] in errno and shall
return ( size_t)-1; the conversion state is undefined. Otherwise, it
shall return the number of characters successfully converted, not including
the terminating null (if any).
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