.\" Copyright (c) 2002 Tim J. Robbins
.\" All rights reserved.
.\"
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.\" modification, are permitted provided that the following conditions
.\" are met:
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.\" $FreeBSD: head/lib/libc/locale/wcwidth.3 133915 2004-08-17 04:56:03Z trhodes $
.\"
.Dd December 27, 2013
.Dt WCWIDTH 3
.Os
.Sh NAME
.Nm wcwidth ,
.Nm wcwidth_l
.Nd "number of column positions of a wide-character code"
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In wchar.h
.Ft int
.Fn wcwidth "wchar_t wc"
.In xlocale.h
.Ft int
.Fn wcwidth_l "wchar_t wc" "locale_t locale"
.Sh DESCRIPTION
The
.Fn wcwidth
and
.Fn wcwidth_l
functions determine the number of column positions required to
display the wide character
.Fa wc .
.Pp
The
.Fn wcwidth_l
function takes an explicit
.Fa locale
argument, whereas the
.Fn wcwidth
function uses the current global or per-thread locale.
.Sh RETURN VALUES
The
.Fn wcwidth
and
.Fn wcwidth_l
functions return 0 if the
.Fa wc
argument is a null wide character (L'\e0'),
\-1 if
.Fa wc
is not printable,
otherwise they return the number of column positions the
character occupies.
.Sh EXAMPLES
This code fragment reads text from standard input and
breaks lines that are more than 20 column positions wide,
similar to the
.Xr fold 1
utility:
.Bd -literal -offset indent
wint_t ch;
int column, w;

column = 0;
while ((ch = getwchar()) != WEOF) {
	w = wcwidth(ch);
	if (w > 0 && column + w >= 20) {
		putwchar(L'\en');
		column = 0;
	}
	putwchar(ch);
	if (ch == L'\en')
		column = 0;
	else if (w > 0)
		column += w;
}
.Ed
.Sh SEE ALSO
.Xr iswprint 3 ,
.Xr wcswidth 3 ,
.Xr xlocale 3
.Sh STANDARDS
The
.Fn wcwidth
function conforms to
.St -p1003.1-2001 .