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.Dd December 19, 2022
.Dt ISUPPER 3
.Os
.Sh NAME
.Nm isupper ,
.Nm isupper_l
.Nd upper-case character test
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In ctype.h
.Ft int
.Fn isupper "int c"
.Ft int
.Fn isupper_l "int c" "locale_t loc"
.Sh DESCRIPTION
The
.Fn isupper
and
.Fn isupper_l
functions test for any upper-case letter.
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):
.Bl -column \&000_``0''__ \&000_``0''__ \&000_``0''__ \&000_``0''__ \&000_``0''__
.It "\&101\ ``A''" Ta "102\ ``B''" Ta "103\ ``C''" Ta "104\ ``D''" Ta "105\ ``E''"
.It "\&106\ ``F''" Ta "107\ ``G''" Ta "110\ ``H''" Ta "111\ ``I''" Ta "112\ ``J''"
.It "\&113\ ``K''" Ta "114\ ``L''" Ta "115\ ``M''" Ta "116\ ``N''" Ta "117\ ``O''"
.It "\&120\ ``P''" Ta "121\ ``Q''" Ta "122\ ``R''" Ta "123\ ``S''" Ta "124\ ``T''"
.It "\&125\ ``U''" Ta "126\ ``V''" Ta "127\ ``W''" Ta "130\ ``X''" Ta "131\ ``Y''"
.It "\&132\ ``Z''" Ta \& Ta \& Ta \& Ta \&
.El
.Pp
The
.Fn isupper_l
function takes an explicit locale argument, whereas the
.Fn isupper
function uses the current global or per-thread locale.
.Sh RETURN VALUES
The
.Fn isupper
and
.Fn isupper_l
functions return zero if the character tests false and
return 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 iswupper
or
.Fn iswupper_l
function should be used instead.
.Sh SEE ALSO
.Xr ctype 3 ,
.Xr ctype_l 3 ,
.Xr iswupper 3 ,
.Xr iswupper_l 3 ,
.Xr toupper 3 ,
.Xr toupper_l 3 ,
.Xr xlocale 3 ,
.Xr ascii 7
.Sh STANDARDS
The
.Fn isupper
function conforms to
.St -isoC .
.Sh HISTORY
The
.Fn isupper
function first appeared in
.At v7 .