'\" t
.\" Copyright, The contributors to the Linux man-pages project
.\"
.\" SPDX-License-Identifier: GPL-2.0-or-later
.\"
.TH wcsnlen 3 2025-05-06 "Linux man-pages 6.14"
.SH NAME
wcsnlen \- determine the length of a fixed-size wide-character string
.SH LIBRARY
Standard C library
.RI ( libc ,\~ \-lc )
.SH SYNOPSIS
.nf
.B #include <wchar.h>
.P
.BI "size_t wcsnlen(size_t " maxlen ;
.BI "               const wchar_t " s [ maxlen "], size_t " maxlen );
.fi
.P
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.P
.BR wcsnlen ():
.nf
    Since glibc 2.10:
        _POSIX_C_SOURCE >= 200809L
    Before glibc 2.10:
        _GNU_SOURCE
.fi
.SH DESCRIPTION
The
.BR wcsnlen ()
function is the wide-character equivalent
of the
.BR strnlen (3)
function.
It returns the number of wide-characters in the string pointed to by
.IR s ,
not including the terminating null wide character (L\[aq]\[rs]0\[aq]),
but at most
.I maxlen
wide characters (note: this parameter is not a byte count).
In doing this,
.BR wcsnlen ()
looks at only the first
.I maxlen
wide characters at
.I s
and never beyond
.IR s[maxlen\-1] .
.SH RETURN VALUE
The
.BR wcsnlen ()
function returns
.IR wcslen(s) ,
if that is less than
.IR maxlen ,
or
.I maxlen
if there is no null wide character among the
first
.I maxlen
wide characters pointed to by
.IR s .
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.na
.nh
.BR wcsnlen ()
T}	Thread safety	MT-Safe
.TE
.SH STANDARDS
POSIX.1-2008.
.SH HISTORY
glibc 2.1.
.SH SEE ALSO
.BR strnlen (3),
.BR wcslen (3)