SAS/C Library Reference, Vol. 1

isxdigit -- Hexadecimal Digit Test

SYNOPSIS

 #include <ctype.h>

 int isxdigit(int c);

DESCRIPTION

isxdigit tests an integer value c to determine whether it is a hexadecimal digit (uppercase or lowercase).

RETURN VALUE

isxdigit returns 0 if the character is not a hexadecimal digit, or a nonzero value if it is. If the argument is EOF, 0 is returned.

CAUTION

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

EXAMPLE

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

  #define IDLEN 40

  main()
  {
     char line[IDLEN];
     char id[IDLEN+1];
     char *text;
     int i;

     puts("Enter a string consisting of hexadecimal characters: ");
     text = gets(line);
        /* Copy from text to id.                                  */
     for (i = 0; i < IDLEN ; ++i) {
        if (isxdigit(text[i]))
           id[i] = text[i];
        else
           id[i] = '*';
     }
     id[i] = '0';

        /* All nonhex characters have been replaced by '*'.       */
     puts("You have entered the following hexadecimal characters:");
     printf("%sn", id);
  }

RELATED FUNCTIONS

isdigit