.\"	$NetBSD: isalpha.3,v 1.14 2008/04/17 16:25:36 apb Exp $
.\"
.\" Copyright (c) 1991 The Regents of the University of California.
.\" All rights reserved.
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.\" This code is derived from software contributed to Berkeley by
.\" the American National Standards Committee X3, on Information
.\" Processing Systems.
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.\"    may be used to endorse or promote products derived from this software
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.\"     @(#)isalpha.3	5.2 (Berkeley) 6/29/91
.\"
.Dd April 17, 2008
.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 and
.\" , or any of an implementation-defined set of characters
for which none of
.Xr iscntrl 3 ,
.Xr isdigit 3 ,
.Xr ispunct 3 ,
or
.Xr isspace 3
is true.
In the
.Em ``C''
locale,
.Fn isalpha
returns true only for the characters for which
.Xr isupper 3
or
.Xr islower 3
is true.
.Sh RETURN VALUES
The
.Fn isalpha
function returns zero if the character tests false and
returns non-zero if the character tests true.
.Sh SEE ALSO
.Xr ctype 3 ,
.Xr isalnum 3 ,
.Xr isascii 3 ,
.Xr isblank 3 ,
.Xr iscntrl 3 ,
.Xr isdigit 3 ,
.Xr isgraph 3 ,
.Xr islower 3 ,
.Xr isprint 3 ,
.Xr ispunct 3 ,
.Xr isspace 3 ,
.Xr isupper 3 ,
.Xr isxdigit 3 ,
.Xr stdio 3 ,
.Xr toascii 3 ,
.Xr tolower 3 ,
.Xr toupper 3 ,
.Xr ascii 7
.Sh STANDARDS
The
.Fn isalpha
function conforms to
.St -ansiC .
.Sh CAVEATS
The argument to
.Fn isalpha
must be
.Dv EOF
or representable as an
.Vt unsigned char ;
otherwise, the behavior is undefined.
See the
.Sx CAVEATS
section of
.Xr ctype 3
for more details.