.\" Copyright (c) 1991, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgement: .\" This product includes software developed by the University of .\" California, Berkeley and its contributors. .\" 4. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)isblank.3 8.1 (Berkeley) 6/4/93 .\" $FreeBSD: src/lib/libc/locale/isblank.3,v 1.19 2004/08/21 07:37:08 tjr Exp $ .\" .Dd August 21, 2004 .Dt ISBLANK 3 .Os .Sh NAME .Nm isblank .Nd space or tab character test .Sh LIBRARY .Lb libc .Sh SYNOPSIS .In ctype.h .Ft int .Fn isblank "int c" .Sh DESCRIPTION The .Fn isblank function tests for a space or tab character. For any locale, this includes the following standard characters: .Pp .Bl -column \&`\et''___ \&``\et''___ .It "\&``\et''\t`` ''" .El .Pp In the "C" locale, .Fn isblank successful test is limited to these characters only. For single C .Va char Ns s locales (see .Xr multibyte 3 ) , the value of the argument is representable as an .Li unsigned char or the value of .Dv EOF . .Sh COMPATIBILITY The .Bx 4.4 extension of accepting arguments outside of the range of the .Vt "unsigned char" type in locales with large character sets is considered obsolete and may not be supported in future releases. The .Fn iswblank function should be used instead. .Sh RETURN VALUES The .Fn isblank function returns zero if the character tests false and returns non-zero if the character tests true. .Sh SEE ALSO .Xr ctype 3 , .Xr isalnum_l 3 , .Xr iswblank 3 , .Xr multibyte 3 , .Xr ascii 7 .Sh STANDARDS The .Fn isblank function conforms to .St -isoC-99 .