Question

Do this using the C language. show me the code being executed and also copy and paste the code so i can try it out for myseld

Instructions A cipher is mirrored algorithm that allow phrases or messages to be obfuscated (ie. "scrambled"). Ciphers were an early form of security used to send hidden messages from one party to another. The most famous and classic example of a cipher is the Caesar Cipher. This cypher worked by shifting each letter in a message over by a certain number of times. For example, in a cipher shift of 4 anys" would be changed to "e", "" "","6"", and so on. Once the messaged reached the recipient, they would reverse the shift to recover the original message. In this assignment, we are going to create a program that apllies the Caesar Cipher to a message stored in a character array. You are going to start with a partially solved program(provided to you on Canvas) that had some of the functionality already implemented. The three functions you need to complete are the following: 1. Main function - You need to write code that calls the encode/decode functions to shift and deshift the message respectively. You must also output the original message, message after it has been encoded, and the message after it has been decoded. The decoded message should be equivelant to the original message. 2. caesar_encode - This function generates the encoding of the original message. It should work by traversing the message(remember strings are arrays as well), and for each character in the array, determine the shifted character and store it in the new stringlie"new_message"). Use the shift_letter function that is already implemented for you to determine the shift of the character. 3. caesar_decode - This function generates the decoding of the original message. It should work by traversing the encoded message(remember strings are arrays as well), and for each character in the array, determine the shifted character and store it in the new stringlie "new_message"). Use the shift_letter function that is already implemented for you to determine the shift of the character. Since this is decoding, you want to remember to reverse shift. The shift_letter function works for negative shifts as well, so you do not have to do anything special to the shift other than negating it. To get credit for this assignment, you MUST start with the skeleton file provided. Failure to do so will result in an immediate zero on this assignment. This is final and no exceptions will be made.

Answer 1

prog6_skeleton.c

#include<stdio.h>
#include<stdlib.h>
char shift_letter(char letter,int shift_amount);
char* caesar_encode(char* message,int message_size,int caesar_shift);
char* caesar_decode(char* encoded_message,int message_size,int caesar_shift);

int main(){

  
   char message[] ="It's a great day to be a bulldog!";
   int size = sizeof(message)/sizeof(message[0]);
  
   int shift_amount = 6;
  
   char *encoded_message=caesar_encode(message,size,shift_amount);
  
   char *decoded_message=caesar_decode(encoded_message,size,shift_amount);
  
   printf("Original message: %s\n",message);
  
   printf("Encoded message: %s\n",encoded_message);
  
   printf("Decoded message: %s\n",decoded_message);
  
   free(encoded_message);
   free(decoded_message);
}

char shift_letter(char letter,int shift_amount){
   int char_index= (int)letter;
  
   if(char_index>=97 && char_index <=122){
      
       int new_posititon=(char_index-97)+shift_amount;
      
       if(new_posititon>=0){
           new_posititon%=26;
           new_posititon=97+new_posititon;
       }else{
      
           new_posititon=26+new_posititon;
           new_posititon=97+new_posititon;
       }
      
       return new_posititon;
   }
  
   else if(char_index>=65 && char_index <=90){
      
       int new_posititon=(char_index-65)+shift_amount;
      
       if(new_posititon>=0){
      
           new_posititon%=26;
           new_posititon=65+new_posititon;
       }else{
      
           new_posititon=26+new_posititon;
           new_posititon=65+new_posititon;
       }
      
       return new_posititon;
   }
   else{

       return letter;  
   }
}

char* caesar_encode(char* message,int message_size,int caesar_shift){

   char* new_message = (char*)malloc(message_size);
   int i;
   for(i=0;i<message_size;i++){
       new_message[i]=shift_letter(message[i],caesar_shift);
   }
  
   return new_message;

}

char* caesar_decode(char* encoded_message,int message_size,int caesar_shift){

   char* new_message = (char*)malloc(message_size);
  
   int i;
   for(i=0;i<message_size;i++){
       new_message[i]=shift_letter(encoded_message[i],-caesar_shift);
   }
  
   return new_message;

}

Output:

original message: It's a great day to be a bulldog! Encoded message: Oz'y g mxkgz jge zu hk g harrjum! Decoded message: It's a great day to be a bulldog!