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.\"     @(#)isalpha.3	8.1 (Berkeley) 6/4/93
.\" $FreeBSD: src/lib/libc/locale/isalpha.3,v 1.23 2009/09/04 07:44:58 des Exp $
.\"
.Dd July 17, 2005
.Dt ISALPHA 3
.Os
.Sh NAME
.Nm isalpha
.Nd alphabetic character test
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In ctype.h
.Ft int
.Fn isalpha "int c"
.Sh DESCRIPTION
The
.Fn isalpha
function tests for any character for which
.Xr isupper 3
or
.Xr islower 3
is true.
The value of the argument must be representable as an
.Vt "unsigned char"
or the value of
.Dv EOF .
.Pp
In the ASCII character set, this includes the following characters
(with their numeric values shown in octal):
.Pp
.Bl -column \&000_``0''__ \&000_``0''__ \&000_``0''__ \&000_``0''__ \&000_``0''__
.It "\&101\ ``A'' \t102\ ``B'' \t103\ ``C'' \t104\ ``D'' \t105\ ``E''"
.It "\&106\ ``F'' \t107\ ``G'' \t110\ ``H'' \t111\ ``I'' \t112\ ``J''"
.It "\&113\ ``K'' \t114\ ``L'' \t115\ ``M'' \t116\ ``N'' \t117\ ``O''"
.It "\&120\ ``P'' \t121\ ``Q'' \t122\ ``R'' \t123\ ``S'' \t124\ ``T''"
.It "\&125\ ``U'' \t126\ ``V'' \t127\ ``W'' \t130\ ``X'' \t131\ ``Y''"
.It "\&132\ ``Z'' \t141\ ``a'' \t142\ ``b'' \t143\ ``c'' \t144\ ``d''"
.It "\&145\ ``e'' \t146\ ``f'' \t147\ ``g'' \t150\ ``h'' \t151\ ``i''"
.It "\&152\ ``j'' \t153\ ``k'' \t154\ ``l'' \t155\ ``m'' \t156\ ``n''"
.It "\&157\ ``o'' \t160\ ``p'' \t161\ ``q'' \t162\ ``r'' \t163\ ``s''"
.It "\&164\ ``t'' \t165\ ``u'' \t166\ ``v'' \t167\ ``w'' \t170\ ``x''"
.It "\&171\ ``y'' \t172\ ``z''"
.El
.Sh RETURN VALUES
The
.Fn isalpha
function returns zero if the character tests false and
returns non-zero if the character tests true.
.Sh COMPATIBILITY
The
.Bx 4.4
extension of accepting arguments outside of the range of the
.Vt "unsigned char"
type in locales with large character sets is considered obsolete
and may not be supported in future releases.
The
.Fn iswalpha
function should be used instead.
.Sh SEE ALSO
.Xr ctype 3 ,
.Xr islower 3 ,
.Xr isupper 3 ,
.Xr iswalpha 3 ,
.Xr ascii 7
.Sh STANDARDS
The
.Fn isalpha
function conforms to
.St -isoC .