islower---lower-case character predicate#include <ctype.h> int islower(int c);Description
islower is a macro which classifies ASCII integer values by table
lookup. It is a predicate returning non-zero for minuscules
(lower-case alphabetic characters), 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 islower'.
Returns
islower returns non-zero if c is a lower case letter (a--z).
Portability
islower is ANSI C.
No supporting OS subroutines are required.