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.TH MBLEN "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

mblen

\(em get number of bytes in a character

.SH SYNOPSIS

.LP

.nf

#include <stdlib.h>

.P

int mblen(const char *\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,

\fImblen\fR()

shall determine the number of bytes constituting the character

pointed to by

.IR s .

Except that the shift state of

\fImbtowc\fR()

is not affected, it shall be equivalent to:

.sp

.RS 4

.nf

\fB

mbtowc((wchar_t *)0, \fIs\fP, \fIn\fP);

.fi \fR

.P

.RE

.P

The implementation shall behave as if no function defined in this volume of POSIX.1\(hy2008

calls

\fImblen\fR().

.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 shall be 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.

.P

The

\fImblen\fR()

function need not be thread-safe.

.SH "RETURN VALUE"

If

.IR s

is a null pointer,

\fImblen\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,

\fImblen\fR()

shall either return 0 (if

.IR s

points to the null byte), or return the number of bytes that

constitute the character (if the next

.IR n

or fewer bytes form a valid character), or return \(mi1 (if they do

not form a valid character)

and may set

.IR errno

to indicate the error.

In no case shall the value returned be greater than

.IR n

or the value of the

{MB_CUR_MAX}

macro.

.SH ERRORS

The

\fImblen\fR()

function may 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 "\fImbtowc\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 .

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 .