DESCRIPTION iscntrl
is a macro which classifies ASCII integer
values by table lookup. It is a predicate returning non-zero for control
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
iscntrl.
RETURNS iscntrl
returns non-zero if c
is a delete character or ordinary control
character (0x7F
or 0x00–0x1F).
