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.\" @(#)isalpha.3 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD$ 34.\" 35.Dd December 19, 2022 36.Dt ISALPHA 3 37.Os 38.Sh NAME 39.Nm isalpha , 40.Nm isalpha_l 41.Nd alphabetic character test 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In ctype.h 46.Ft int 47.Fn isalpha "int c" 48.Ft int 49.Fn isalpha_l "int c" "locale_t loc" 50.Sh DESCRIPTION 51The 52.Fn isalpha 53and 54.Fn isalpha_l 55functions test for any character for which 56.Xr isupper 3 , 57.Xr isupper_l 3 58or 59.Xr islower 3 , 60.Xr islower_l 3 61is true. 62The value of the argument must be representable as an 63.Vt "unsigned char" 64or the value of 65.Dv EOF . 66.Pp 67In the ASCII character set, this includes the following characters 68(with their numeric values shown in octal): 69.Bl -column \&000_``0''__ \&000_``0''__ \&000_``0''__ \&000_``0''__ \&000_``0''__ 70.It "\&101\ ``A''" Ta "102\ ``B''" Ta "103\ ``C''" Ta "104\ ``D''" Ta "105\ ``E''" 71.It "\&106\ ``F''" Ta "107\ ``G''" Ta "110\ ``H''" Ta "111\ ``I''" Ta "112\ ``J''" 72.It "\&113\ ``K''" Ta "114\ ``L''" Ta "115\ ``M''" Ta "116\ ``N''" Ta "117\ ``O''" 73.It "\&120\ ``P''" Ta "121\ ``Q''" Ta "122\ ``R''" Ta "123\ ``S''" Ta "124\ ``T''" 74.It "\&125\ ``U''" Ta "126\ ``V''" Ta "127\ ``W''" Ta "130\ ``X''" Ta "131\ ``Y''" 75.It "\&132\ ``Z''" Ta "141\ ``a''" Ta "142\ ``b''" Ta "143\ ``c''" Ta "144\ ``d''" 76.It "\&145\ ``e''" Ta "146\ ``f''" Ta "147\ ``g''" Ta "150\ ``h''" Ta "151\ ``i''" 77.It "\&152\ ``j''" Ta "153\ ``k''" Ta "154\ ``l''" Ta "155\ ``m''" Ta "156\ ``n''" 78.It "\&157\ ``o''" Ta "160\ ``p''" Ta "161\ ``q''" Ta "162\ ``r''" Ta "163\ ``s''" 79.It "\&164\ ``t''" Ta "165\ ``u''" Ta "166\ ``v''" Ta "167\ ``w''" Ta "170\ ``x''" 80.It "\&171\ ``y''" Ta "172\ ``z''" Ta \& Ta \& Ta \& 81.El 82.Pp 83The 84.Fn isalpha_l 85function takes an explicit locale argument, whereas the 86.Fn isalpha 87function uses the current global or per-thread locale. 88.Sh RETURN VALUES 89The 90.Fn isalpha 91and 92.Fn isalpha_l 93functions return zero if the character tests false and 94return non-zero if the character tests true. 95.Sh COMPATIBILITY 96The 97.Bx 4.4 98extension of accepting arguments outside of the range of the 99.Vt "unsigned char" 100type in locales with large character sets is considered obsolete 101and may not be supported in future releases. 102The 103.Fn iswalpha 104or 105.Fn iswalpha_l 106function should be used instead. 107.Sh SEE ALSO 108.Xr ctype 3 , 109.Xr ctype_l 3 , 110.Xr islower 3 , 111.Xr islower_l 3 , 112.Xr isupper 3 , 113.Xr isupper_l 3 , 114.Xr iswalpha 3 , 115.Xr iswalpha_l 3 , 116.Xr xlocale 3 , 117.Xr ascii 7 118.Sh STANDARDS 119The 120.Fn isalpha 121function conforms to 122.St -isoC . 123The 124.Fn isalpha_l 125function conforms to 126.St -p1003.1-2008 . 127