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[unix-history] / usr / src / lib / libc / gen / isalpha.3

.\" Copyright (c) 1991 The Regents of the University of California.
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.\" This code is derived from software contributed to Berkeley by
.\" the American National Standards Committee X3, on Information
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.\"     @(#)isalpha.3	5.2 (Berkeley) 6/29/91
.\"
.Dd June 29, 1991
.Dt ISALPHA 3
.Os
.Sh NAME
.Nm isalpha
.Nd alphabetic character test
.Sh SYNOPSIS
.Fd #include <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
macro returns zero if the character tests false and
returns non-zero if the character tests true.
.Sh SEE ALSO
.Xr isascii 3 ,
.Xr isalnum 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 toascii 3 ,
.Xr tolower 3 ,
.Xr toupper 3 ,
.Xr stdio 3
.Xr ascii 7
.Sh STANDARDS
The
.Fn isalpha
function conforms to
.St -ansiC .