NAME
mbtowc - convert a character to a wide-character code
SYNOPSIS
#include <stdlib.h>
int mbtowc(wchar_t *restrict pwc, const char *restrict s, size_t n);
DESCRIPTION
If s is not a null pointer, mbtowc() shall determine the number of
bytes that constitute the character pointed to by s. It shall then
determine the wide-character code for the value of type wchar_t that
corresponds to that character. (The value of the wide-character code
corresponding to the null byte is 0.) If the character is valid and pwc
is not a null pointer, mbtowc() shall store the wide-character code in
the object pointed to by pwc.
The behavior of this function is affected by the LC_CTYPE category of
the current locale. For a state-dependent encoding, this function is
placed into its initial state by a call for which its character pointer
argument, s, is a null pointer. Subsequent calls with s as other than
a null pointer shall cause the internal state of the function to be
altered as necessary. A call with s as a null pointer shall cause this
function to return a non-zero value if encodings have state dependency,
and 0 otherwise. If the implementation employs special bytes to change
the shift state, these bytes shall not produce separate wide-character
codes, but shall be grouped with an adjacent character. Changing the
LC_CTYPE category causes the shift state of this function to be
unspecified. At most n bytes of the array pointed to by s shall be
examined.
The implementation shall behave as if no function defined in this
volume of IEEE Std 1003.1-2001 calls mbtowc().
RETURN VALUE
If s is a null pointer, mbtowc() shall return a non-zero or 0 value, if
character encodings, respectively, do or do not have state-dependent
encodings. If s is not a null pointer, mbtowc() shall either return 0
(if s points to the null byte), or return the number of bytes that
constitute the converted character (if the next n or fewer bytes form a
valid character), or return -1 and may set errno to indicate the
error (if they do not form a valid character).
In no case shall the value returned be greater than n or the value of
the {MB_CUR_MAX} macro.
ERRORS
The mbtowc() function may fail if:
EILSEQ Invalid character sequence is detected.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
None.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
mblen() , mbstowcs() , wctomb() , wcstombs() , the Base Definitions
volume of IEEE Std 1003.1-2001, <stdlib.h>
COPYRIGHT
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 .