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. 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.\" 34.Dd December 19, 2022 35.Dt ISCNTRL 3 36.Os 37.Sh NAME 38.Nm iscntrl , 39.Nm iscntrl_l 40.Nd control character test 41.Sh LIBRARY 42.Lb libc 43.Sh SYNOPSIS 44.In ctype.h 45.Ft int 46.Fn iscntrl "int c" 47.Ft int 48.Fn iscntrl_l "int c" "locale_t loc" 49.Sh DESCRIPTION 50The 51.Fn iscntrl 52and 53.Fn iscntrl_l 54functions test 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.Bl -column \&000_``0''__ \&000_``0''__ \&000_``0''__ \&000_``0''__ \&000_``0''__ 63.It "\&000\ NUL" Ta "001\ SOH" Ta "002\ STX" Ta "003\ ETX" Ta "004\ EOT" 64.It "\&005\ ENQ" Ta "006\ ACK" Ta "007\ BEL" Ta "010\ BS" Ta "011\ HT" 65.It "\&012\ NL" Ta "013\ VT" Ta "014\ NP" Ta "015\ CR" Ta "016\ SO" 66.It "\&017\ SI" Ta "020\ DLE" Ta "021\ DC1" Ta "022\ DC2" Ta "023\ DC3" 67.It "\&024\ DC4" Ta "025\ NAK" Ta "026\ SYN" Ta "027\ ETB" Ta "030\ CAN" 68.It "\&031\ EM" Ta "032\ SUB" Ta "033\ ESC" Ta "034\ FS" Ta "035\ GS" 69.It "\&036\ RS" Ta "037\ US" Ta "177\ DEL" Ta \& Ta \& 70.El 71.Pp 72The 73.Fn iscntrl_l 74function takes an explicit locale argument, whereas the 75.Fn iscntrl 76function uses the current global or per-thread locale. 77.Sh RETURN VALUES 78The 79.Fn iscntrl 80and 81.Fn iscntrl_l 82functions return zero if the character tests false and 83return non-zero if the character tests true. 84.Sh COMPATIBILITY 85The 86.Bx 4.4 87extension of accepting arguments outside of the range of the 88.Vt "unsigned char" 89type in locales with large character sets is considered obsolete 90and may not be supported in future releases. 91The 92.Fn iswcntrl 93or 94.Fn iswcntrl_l 95function should be used instead. 96.Sh SEE ALSO 97.Xr ctype 3 , 98.Xr ctype_l 3 , 99.Xr iswcntrl 3 , 100.Xr iswcntrl_l 3 , 101.Xr xlocale 3 , 102.Xr ascii 7 103.Sh STANDARDS 104The 105.Fn iscntrl 106function conforms to 107.St -isoC . 108The 109.Fn iscntrl_l 110function conforms to 111.St -p1003.1-2008 . 112.Sh HISTORY 113The 114.Fn iscntrl 115function first appeared in 116.At v7 . 117