C iscntrl function checks if a character is a control letter or not

Syntax

C iscntrl function has the following syntax.

Header

C iscntrl function is from header file ctype.h.

Description

C iscntrl function returns nonzero if ch is a control character or zero is returned.

Example

The following code uses C iscntrl function to check if a character is a control letter.

#include <ctype.h>
#include <stdio.h>
//from  w ww .j  a v  a  2  s .c om
int main(void)
{
  char ch;

  for(;;) {
     ch = getchar( );
     if(ch == '.') {
        break;
     }
     if(iscntrl(ch)){
        printf("%c is a control char\n", ch);
     }
  }

  return 0;
}

The code above generates the following result.