/*
 *  simpleEncode.c
 *
 *  reads in a permutation of the alphabet then encodes
 *  lower case letters using that permutation
 *  module 4 template code you asked for - might need some cleaning up..
 *
 *  Created by Julian Saknussemm on 11/09/1752
 *  Licensed under Creative Commons BY 3.0.
 *
 */

// by Sabrina Rispin
// Activity Section: 4
// Date: 28/3/15
// Description: Encodes letters based on an entered permutaion of the 
// alphabet.

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <string.h>

#define STOP -1
#define ALPHABET_SIZE 26
#define FIRST_LC 'a'
#define LAST_LC 'z'
#define FIRST_UC 'A'
#define LAST_UC 'Z'

char encode (int plainChar, char *permuation);
void testEncode (void);

int main (int argc, char *argv[]) {

   testEncode();

   char permutation[ALPHABET_SIZE];

   scanf ("%s", permutation);
   while (strlen (permutation) != ALPHABET_SIZE) {
      printf ("Please enter a string as long as the alphabet\n");
      scanf ("%s", permutation);
   }

   // getchar() reads and returns one character from the keyboard
   // returns -1 when the input is finished / end-of-file is reached
   // signal this from the kayboard by pressing ^D in linux/^Z windows
   int plainCharacter = getchar();
   int encodedCharacter;
   while (plainCharacter != STOP) {
      if (plainCharacter >= FIRST_LC && plainCharacter <= LAST_LC) {
         encodedCharacter = encode (plainCharacter, permutation);  
      } else {
         encodedCharacter = plainCharacter;
      }
      printf ("%c", encodedCharacter);
      plainCharacter = getchar();
   }
   return EXIT_SUCCESS;
}

void testEncode (void) {
   assert (encode ('A',"abcdefghijklmnopqrstuvwxyz") == 'A');
   assert (encode ('?',"abcdefghijklmnopqrstuvwxyz") == '?');
   assert (encode (' ',"abcdefghijklmnopqrstuvwxyz") == ' ');
   assert (encode ('\n',"abcdefghijklmnopqrstuvwxyz") == '\n');

   assert (encode ('a',"abcdefghijklmnopqrstuvwxyz") == 'a');
   assert (encode ('m',"abcdefghijklmnopqrstuvwxyz") == 'm');
   assert (encode ('z',"abcdefghijklmnopqrstuvwxyz") == 'z');

   assert (encode ('a',"bcdefghijklmnopqrstuvwxyza") == 'b');
   assert (encode ('m',"bcdefghijklmnopqrstuvwxyza") == 'n');
   assert (encode ('z',"bcdefghijklmnopqrstuvwxyza") == 'a');

   assert (encode ('a',"qwertyuiopasdfghjklzxcvbnm") == 'q');
   assert (encode ('b',"qwertyuiopasdfghjklzxcvbnm") == 'w');
   assert (encode ('z',"qwertyuiopasdfghjklzxcvbnm") == 'm');
}

char encode (int plainChar, char *permuation) {
   char encodedChar;
   int charNum = plainChar - FIRST_LC;

   if (plainChar >= FIRST_LC && plainChar <= LAST_LC) {
      encodedChar = permuation[charNum];
   } else {
      encodedChar = plainChar;
   }
   
   return encodedChar;
}

Download file: simpleEncode.c (2.7 KB)

Sabrina Rispin – edited Sat, Mar 28 2015 3:31 p.m. – history