iscntrl

iscntrl

Control Character Test

Portability: ISO/ANSI C conforming, UNIX compatible

SYNOPSIS
DESCRIPTION
RETURN VALUE
CAUTION
PORTABILITY
IMPLEMENTATION
EXAMPLE
RELATED FUNCTIONS
SEE ALSO

SYNOPSIS

#include <ctype.h>

int iscntrl(int c);

DESCRIPTION

iscntrl tests an integer value c to determine whether it is a control character.

RETURN VALUE

iscntrl returns 0 if the character is not a control character, or a nonzero value if it is. If the argument is EOF , 0 is returned.

CAUTION

The effect of iscntrl on a noncharacter argument other than EOF is undefined. Do not assume that iscntrl returns either 0 or 1.

Note: For some EBCDIC characters, neither iscntrl(c) nor isprint(c) is true, even though this identity is sometimes used as a definition of isprint . [cautionend]

PORTABILITY

You should carefully examine the iscntrl function when using it in a program that is expected to be portable. IBM uses the words control character to designate characters between 0x00 and 0x3f , as well as 0xff . This implementation defines iscntrl('\xff') as false.

IMPLEMENTATION

iscntrl is implemented by a macro. iscntrl tests a character to see whether it is less than a blank in the EBCDIC collating sequence. This is true for the EBCDIC equivalents of all ASCII control characters.

EXAMPLE

#include <ctype.h>
#include <stdio.h>

main()
{
   char *buf;

   buf = "Hello World. \n This is a test. ";

   do {
   if (!iscntrl(*buf))
      putchar(*buf);
   else
      putchar('*');
   buf++;
   } while (*buf);
   putchar("\n");
}

RELATED FUNCTIONS

isspace

SEE ALSO

Character Type Macros and Functions

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