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.\"     @(#)isalpha.3	8.1 (Berkeley) 6/4/93
.\" $FreeBSD: src/lib/libc/locale/isalpha.3,v 1.18 2004/08/21 07:37:08 tjr Exp $
.\"
.Dd August 21, 2004
.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.
For single C
.Va char Ns s
locales (see
.Xr multibyte 3 ) ,
the value of the argument is
representable as an
.Li unsigned char
or the value of
.Dv EOF .
In the ASCII character set, this includes the following characters
(preceded by their numeric values, 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 isalnum_l 3 ,
.Xr islower 3 ,
.Xr isupper 3 ,
.Xr iswalpha 3 ,
.Xr multibyte 3 ,
.Xr ascii 7
.Sh STANDARDS
The
.Fn isalpha
function conforms to
.St -isoC .