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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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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.1‐2017 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.1‐2017 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. In the POSIX
locale an [EILSEQ] error cannot occur since all byte values
are valid characters.
The following sections are informative.
None.
None.
None.
None.
mblen(3p), mbstowcs(3p), wctomb(3p), wcstombs(3p)
The Base Definitions volume of POSIX.1‐2017, stdlib.h(0p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 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 .
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 2017 MBTOWC(3P)
Pages that refer to this page: ctype.h(0p), stdlib.h(0p), mblen(3p), mbstowcs(3p), setlocale(3p), wcstombs(3p), wctomb(3p)
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HTML rendering created 2025-02-02 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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