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MBTOWC(3P) POSIX Programmer's Manual MBTOWC(3P)
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.
mbtowc — convert a character to a wide-character code
#include <stdlib.h>
int mbtowc(wchar_t *restrict pwc, const char *restrict s, size_t n);
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.
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 POSIX.1‐2008 calls mbtowc().
The mbtowc() function need not be thread-safe.
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 shall 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.
The mbtowc() function shall fail if:
EILSEQ An invalid character sequence is detected.
The following sections are informative.
None.
None.
None.
None.
mblen(3p), mbstowcs(3p), wctomb(3p), wcstombs(3p)
The Base Definitions volume of POSIX.1‐2008, stdlib.h(0p)
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
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 MBTOWC(3P)
Pages that refer to this page: ctype.h(0p), stdlib.h(0p), mblen(3p), mbstowcs(3p), setlocale(3p), wcstombs(3p), wctomb(3p)