isupper, isupper_l—uppercase character predicateSynopsis
#include <ctype.h> int isupper(int c); #include <ctype.h> int isupper_l(int c, locale_t locale);
Description
isupper is a macro which classifies singlebyte charset values by table
lookup. It is a predicate returning non-zero for uppercase letters
(A–Z), and 0 for other characters.
isupper_l is like isupper but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
You can use a compiled subroutine instead of the macro definition by
undefining the macro using ‘#undef isupper’ or ‘#undef isupper_l’.
Returns
isupper, isupper_l return non-zero if c is an uppercase letter.
Portability
isupper is ANSI C.
isupper_l is POSIX-1.2008.
No supporting OS subroutines are required.