.\" 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: src/lib/libc/locale/wcwidth.3,v 1.6 2004/08/17 04:56:03 trhodes Exp $
.\"
.Dd August 17, 2004
.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
.Fo wcwidth
.Fa "wchar_t wc"
.Fc
.In wchar.h
.In xlocale.h
.Ft int
.Fo wcwidth_l
.Fa "wchar_t wc"
.Fa "locale_t loc"
.Fc
.Sh DESCRIPTION
The
.Fn wcwidth
function determines the number of column positions required to
display the wide character
.Fa wc .
.Pp
Although the
.Fn wcwidth
function uses the current locale, the
.Fn wcwidth_l
function may be passed a locale directly. See
.Xr xlocale 3
for more information.
.Sh RETURN VALUES
The
.Fn wcwidth
function returns 0 if the
.Fa wc
argument is a null wide character (L'\e0'),
\-1 if
.Fa wc
is not printable;
otherwise, it returns 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 .