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