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.TH MBTOWC "3P" 2013 "IEEE/The Open Group" "POSIX Programmer's Manual"
.SH PROLOG
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.

.SH NAME
mbtowc
\(em convert a character to a wide-character code
.SH SYNOPSIS
.LP
.nf
#include <stdlib.h>
.P
int mbtowc(wchar_t *restrict \fIpwc\fP, const char *restrict \fIs\fP, size_t \fIn\fP);
.fi
.SH DESCRIPTION
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\(hy2008 defers to the ISO\ C standard.
.P
If
.IR s
is not a null pointer,
\fImbtowc\fR()
shall determine the number of bytes that constitute the character
pointed to by
.IR s .
It shall then determine the wide-character code for the value of type
.BR 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
.IR pwc
is not a null pointer,
\fImbtowc\fR()
shall store the wide-character code in the object pointed to by
.IR pwc .
.P
The behavior of this function is affected by the
.IR 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,
.IR s ,
is a null pointer. Subsequent calls with
.IR s
as other than a null pointer shall cause the internal state of the
function to be altered as necessary. A call with
.IR 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
.IR LC_CTYPE
category causes the shift state of this function to be unspecified. At
most
.IR n
bytes of the array pointed to by
.IR s
shall be examined.
.P
The implementation shall behave as if no function defined in this volume of POSIX.1\(hy2008 calls
\fImbtowc\fR().
.P
The
\fImbtowc\fR()
function need not be thread-safe.
.SH "RETURN VALUE"
If
.IR s
is a null pointer,
\fImbtowc\fR()
shall return a non-zero or 0 value, if character encodings, respectively,
do or do not have state-dependent encodings. If
.IR s
is not a null pointer,
\fImbtowc\fR()
shall either return 0 (if
.IR s
points to the null byte), or return the number of bytes that constitute
the converted character (if the next
.IR n
or fewer bytes form a valid character), or return \(mi1
and shall set
.IR errno
to indicate the error
(if they do not form a valid character).
.P
In no case shall the value returned be greater than
.IR n
or the value of the
{MB_CUR_MAX}
macro.
.SH ERRORS
The
\fImbtowc\fR()
function shall fail if:
.TP
.BR EILSEQ
An invalid character sequence is detected.
.LP
.IR "The following sections are informative."
.SH EXAMPLES
None.
.SH "APPLICATION USAGE"
None.
.SH RATIONALE
None.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "\fImblen\fR\^(\|)",
.IR "\fImbstowcs\fR\^(\|)",
.IR "\fIwctomb\fR\^(\|)",
.IR "\fIwcstombs\fR\^(\|)"
.P
The Base Definitions volume of POSIX.1\(hy2008,
.IR "\fB<stdlib.h>\fP"
.SH COPYRIGHT
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 .

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