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iscntrl
[control character predicate]

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

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).

COMPLIANCE
iscntrl is ANSI C.

No supporting OS subroutines are required.