/* File: crunch.c
   An implementation of the Captain Crunch
   secret decoder ring.
*/
#include <stdio.h>
#include "simpio.h"
#include "genlib.h"
#include "strlib.h"

main() {
   string str ;
   int index, i ;
   char c ;
   /* Initialize our code */
   char code[26] = 
        {'t','f','h','x','q','j','e','m','u','p',
         'i','d','c','k','v','b','a','o','l','r',
         'z','w','g','n','s','y'} ;

   /* Get Input */
   printf("Enter a line: ") ;
   str = GetLine() ;

   /* Encrypt */
   for (i = 0 ; str[i] != '\0' ; i++) {
      if ( isalpha(str[i]) ) {
	c = tolower(str[i]) ;
	index = (int) c - 'a' ;
	str[i] = code[index] ;  
      } 
   }
   printf("   Encrypted: %s\n", str ) ;

   /* Decrypt */
   for (i = 0 ; str[i] != '\0' ; i++) {
      if ( isalpha(str[i]) ) {

	c = tolower(str[i]) ;

	/* find matching character */
	for (index = 0 ; index < 26 ; index++) {
	   if ( code[index] == c ) {
	      str[i] = (char) 'a' + index ;
	   } /* if */
	} /* for */

      } /* if ( isalpha ... ) */ 
   } /* for */
   printf("   Decrypted: %s\n", str ) ;
}