1.\" Copyright (c) 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" the American National Standards Committee X3, on Information 6.\" Processing Systems. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. All advertising materials mentioning features or use of this software 17.\" must display the following acknowledgement: 18.\" This product includes software developed by the University of 19.\" California, Berkeley and its contributors. 20.\" 4. Neither the name of the University nor the names of its contributors 21.\" may be used to endorse or promote products derived from this software 22.\" without specific prior written permission. 23.\" 24.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34.\" SUCH DAMAGE. 35.\" 36.\" @(#)iscntrl.3 8.1 (Berkeley) 6/4/93 37.\" $FreeBSD$ 38.\" 39.Dd July 17, 2005 40.Dt ISCNTRL 3 41.Os 42.Sh NAME 43.Nm iscntrl 44.Nd control character test 45.Sh LIBRARY 46.Lb libc 47.Sh SYNOPSIS 48.In ctype.h 49.Ft int 50.Fn iscntrl "int c" 51.Sh DESCRIPTION 52The 53.Fn iscntrl 54function tests for any control character. 55The value of the argument must be representable as an 56.Vt unsigned char 57or the value of 58.Dv EOF . 59.Pp 60In the ASCII character set, this includes the following characters 61(with their numeric values shown in octal): 62.Pp 63.Bl -column \&000_``0''__ \&000_``0''__ \&000_``0''__ \&000_``0''__ \&000_``0''__ 64.It "\&000\ NUL \t001\ SOH \t002\ STX \t003\ ETX \t004\ EOT" 65.It "\&005\ ENQ \t006\ ACK \t007\ BEL \t010\ BS \t011\ HT" 66.It "\&012\ NL \t013\ VT \t014\ NP \t015\ CR \t016\ SO" 67.It "\&017\ SI \t020\ DLE \t021\ DC1 \t022\ DC2 \t023\ DC3" 68.It "\&024\ DC4 \t025\ NAK \t026\ SYN \t027\ ETB \t030\ CAN" 69.It "\&031\ EM \t032\ SUB \t033\ ESC \t034\ FS \t035\ GS" 70.It "\&036\ RS \t037\ US \t177\ DEL" 71.El 72.Sh RETURN VALUES 73The 74.Fn iscntrl 75function returns zero if the character tests false and 76returns non-zero if the character tests true. 77.Sh COMPATIBILITY 78The 79.Bx 4.4 80extension of accepting arguments outside of the range of the 81.Vt "unsigned char" 82type in locales with large character sets is considered obsolete 83and may not be supported in future releases. 84The 85.Fn iswcntrl 86function should be used instead. 87.Sh SEE ALSO 88.Xr ctype 3 , 89.Xr iswcntrl 3 , 90.Xr ascii 7 91.Sh STANDARDS 92The 93.Fn iscntrl 94function conforms to 95.St -isoC . 96