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iscntrl
NAME
iscntrl - check for a control character
SYNOPSIS
int r = iscntrl(c);
int c;
This is a MACRO if you #include <ctype.h>, a subroutine call if
you do not.
FUNCTION
Returns non-zero if the character is a control character (0-31),
zero if it is not.
NOTE
When a non-zero value is returned, this value can be *anything*
other than zero. It is not necessarily a 1. It is guarenteed to
fit in a short, however, and still remain non-zero.
characters in the 128-255 range are valid inputs. characters
less than -1 or larger than 255 are ILLEGAL and the results will
be random. If you are passing a CHAR, you must cast it to an
UNSIGNED CHAR first.
EOF is a valid input an always returns false
EXAMPLE
#include <ctype.h>
#include <assert.h>
main()
{
assert(iscntrl(10));
assert(iscntrl(8));
assert(!iscntrl('1'));
assert(!iscntrl('%'));
}
INPUTS
int c; character that we are checking
RESULTS
int r; 0 if the check failed, non-zero if the check is true