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.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)iscntrl.3 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD: head/lib/libc/locale/iscntrl.3 233992 2012-04-07 09:05:30Z joel $ 34.\" 35.Dd July 17, 2005 36.Dt ISCNTRL 3 37.Os 38.Sh NAME 39.Nm iscntrl , 40.Nm iscntrl_l 41.Nd control character test 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In ctype.h 46.Ft int 47.Fn iscntrl "int c" 48.In ctype.h 49.In xlocale.h 50.Ft int 51.Fn iscntrl_l "int c" "locale_t loc" 52.Sh DESCRIPTION 53The 54.Fn iscntrl 55function tests for any control character. 56The value of the argument must be representable as an 57.Vt "unsigned char" 58or the value of 59.Dv EOF . 60.Pp 61In the ASCII character set, this includes the following characters 62(with their numeric values shown in octal): 63.Bl -column \&000_``0''__ \&000_``0''__ \&000_``0''__ \&000_``0''__ \&000_``0''__ 64.It "\&000\ NUL" Ta "001\ SOH" Ta "002\ STX" Ta "003\ ETX" Ta "004\ EOT" 65.It "\&005\ ENQ" Ta "006\ ACK" Ta "007\ BEL" Ta "010\ BS" Ta "011\ HT" 66.It "\&012\ NL" Ta "013\ VT" Ta "014\ NP" Ta "015\ CR" Ta "016\ SO" 67.It "\&017\ SI" Ta "020\ DLE" Ta "021\ DC1" Ta "022\ DC2" Ta "023\ DC3" 68.It "\&024\ DC4" Ta "025\ NAK" Ta "026\ SYN" Ta "027\ ETB" Ta "030\ CAN" 69.It "\&031\ EM" Ta "032\ SUB" Ta "033\ ESC" Ta "034\ FS" Ta "035\ GS" 70.It "\&036\ RS" Ta "037\ US" Ta "177\ DEL" Ta \& Ta \& 71.El 72.Pp 73The 74.Fn iscntrl_l 75function takes an explicit locale argument, whereas the 76.Fn iscntrl 77function uses the current global or per-thread locale. 78.Sh RETURN VALUES 79The 80.Fn iscntrl 81function returns zero if the character tests false and 82returns non-zero if the character tests true. 83.Sh COMPATIBILITY 84The 85.Bx 4.4 86extension of accepting arguments outside of the range of the 87.Vt "unsigned char" 88type in locales with large character sets is considered obsolete 89and may not be supported in future releases. 90The 91.Fn iswcntrl 92function should be used instead. 93.Sh SEE ALSO 94.Xr ctype 3 , 95.Xr ctype_l 3 , 96.Xr iswcntrl 3 , 97.Xr xlocale 3 , 98.Xr ascii 7 99.Sh STANDARDS 100The 101.Fn iscntrl 102function conforms to 103.St -isoC . 104The 105.Fn iscntrl_l 106function conforms to 107.St -p1003.1-2008 . 108