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.Dd December 19, 2022 33.Dt ISLOWER 3 34.Os 35.Sh NAME 36.Nm islower , 37.Nm islower_l 38.Nd lower-case character test 39.Sh LIBRARY 40.Lb libc 41.Sh SYNOPSIS 42.In ctype.h 43.Ft int 44.Fn islower "int c" 45.Ft int 46.Fn islower_l "int c" "locale_t loc" 47.Sh DESCRIPTION 48The 49.Fn islower 50and 51.Fn islower_l 52functions test for any lower-case letters. 53The value of the argument must be representable as an 54.Vt "unsigned char" 55or the value of 56.Dv EOF . 57.Pp 58In the ASCII character set, this includes the following characters 59(with their numeric values shown in octal): 60.Bl -column \&000_``0''__ \&000_``0''__ \&000_``0''__ \&000_``0''__ \&000_``0''__ 61.It "\&141\ ``a''" Ta "142\ ``b''" Ta "143\ ``c''" Ta "144\ ``d''" Ta "145\ ``e''" 62.It "\&146\ ``f''" Ta "147\ ``g''" Ta "150\ ``h''" Ta "151\ ``i''" Ta "152\ ``j''" 63.It "\&153\ ``k''" Ta "154\ ``l''" Ta "155\ ``m''" Ta "156\ ``n''" Ta "157\ ``o''" 64.It "\&160\ ``p''" Ta "161\ ``q''" Ta "162\ ``r''" Ta "163\ ``s''" Ta "164\ ``t''" 65.It "\&165\ ``u''" Ta "166\ ``v''" Ta "167\ ``w''" Ta "170\ ``x''" Ta "171\ ``y''" 66.It "\&172\ ``z''" Ta \& Ta \& Ta \& Ta \& 67.El 68The 69.Fn islower_l 70function takes an explicit locale argument, whereas the 71.Fn islower 72function uses the current global or per-thread locale. 73.Sh RETURN VALUES 74The 75.Fn islower 76and 77.Fn islower_l 78functions return zero if the character tests false and 79return non-zero if the character tests true. 80.Sh COMPATIBILITY 81The 82.Bx 4.4 83extension of accepting arguments outside of the range of the 84.Vt "unsigned char" 85type in locales with large character sets is considered obsolete 86and may not be supported in future releases. 87The 88.Fn iswlower 89or 90.Fn iswlower_l 91function should be used instead. 92.Sh SEE ALSO 93.Xr ctype 3 , 94.Xr ctype_l 3 , 95.Xr iswlower 3 , 96.Xr iswlower_l 3 , 97.Xr tolower 3 , 98.Xr tolower_l 3 , 99.Xr xlocale 3 , 100.Xr ascii 7 101.Sh STANDARDS 102The 103.Fn islower 104function conforms to 105.St -isoC . 106The 107.Fn islower_l 108function conforms to 109.St -p1003.1-2008 . 110.Sh HISTORY 111The 112.Fn islower 113function first appeared in 114.At v7 . 115