iscntrl, iscntrl_l—control character predicate #include <ctype.h>
int iscntrl(int c);
#include <ctype.h>
int iscntrl_l(int c, locale_t locale);
Description
iscntrl is a macro which classifies singlebyte charset values by table
lookup. It is a predicate returning non-zero for control characters, and 0
for other characters. It is defined only if c is representable as an
unsigned char or if c is EOF.
iscntrl_l is like iscntrl 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 iscntrl' or `#undef iscntrl_l'.
Returns
iscntrl, iscntrl_l return non-zero if c is a delete character
or ordinary control character.
Portability
iscntrl is ANSI C.
iscntrl_l is POSIX-1.2008.
No supporting OS subroutines are required.