SAS/C Library Reference, Vol. 1

iscntrl -- Control Character Test

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.

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