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isupper
[uppercase character predicate]

SYNOPSIS
#include <ctype.h>
int isupper(int c);

DESCRIPTION
isupper is a macro which classifies ASCII integer values by table lookup. It is a predicate returning non-zero for uppercase letters (A–Z), and 0 for other characters. It is defined only when isascii(c) is true or c is EOF.

You can use a compiled subroutine instead of the macro definition by undefining the macro, using #undef isupper.

RETURNS
isupper returns non-zero if c is a upper case letter (A-Z).

COMPLIANCE
isupper is ANSI C.

No supporting OS subroutines are required.