.\"	$OpenBSD: isupper.3,v 1.14 2017/09/05 03:16:13 schwarze Exp $
.\"
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.\" Copyright (c) 2017 Ingo Schwarze <schwarze@openbsd.org>
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.Dd $Mdocdate: September 5 2017 $
.Dt ISUPPER 3
.Os
.Sh NAME
.Nm isupper ,
.Nm isupper_l
.Nd upper-case singly-byte character test
.Sh SYNOPSIS
.In ctype.h
.Ft int
.Fn isupper "int c"
.Ft int
.Fn isupper_l "int c" "locale_t locale"
.Sh DESCRIPTION
The
.Fn isupper
and
.Fn isupper_l
functions test whether
.Fa c
represents an upper-case letter.
.Pp
In the C locale, the complete list of upper-case letters is A\(enZ.
.Ox
always uses the C locale for these functions,
ignoring the global locale, the thread-specific locale, and the
.Fa locale
argument.
.Sh RETURN VALUES
These functions return zero if the character tests false or
non-zero if the character tests true.
.Sh ENVIRONMENT
On systems supporting non-ASCII single-byte character encodings,
these functions may return non-zero for additional characters,
and the results of
.Fn isupper
may depend on the
.Ev LC_CTYPE
.Xr locale 1 ,
but they never return non-zero for any character for which
.Xr iscntrl 3 ,
.Xr isdigit 3 ,
.Xr ispunct 3 ,
or
.Xr isspace 3
is true.
.Sh SEE ALSO
.Xr isalnum 3 ,
.Xr isalpha 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 iswupper 3 ,
.Xr isxdigit 3 ,
.Xr stdio 3 ,
.Xr toascii 3 ,
.Xr tolower 3 ,
.Xr toupper 3 ,
.Xr ascii 7
.Sh STANDARDS
The
.Fn isupper
function conforms to
.St -ansiC ,
and
.Fn isupper_l
to
.St -p1003.1-2008 .
.Sh HISTORY
The
.Fn isupper
function first appeared in
.At v7 ,
and
.Fn isupper_l
has been available since
.Ox 6.2 .
.Sh CAVEATS
The argument
.Fa c
must be
.Dv EOF
or representable as an
.Li unsigned char ;
otherwise, the result is undefined.