UdemyChallenge.cpp

# include <iostream>
#include <cstring>
using namespace std;
int main()
{
  int choice;
  char alphabets[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
  char key[]= "bdafzLPmNRxTcVQX+UWSKMpFknHy*EGIqZhtvYDgrCulAwoBsjei_";
  char encrypted_message[50];
  char decrypted_message[50];  
  do{  
      cout << "1.Encrypt the message.\n2.Decrypt the message.\n3.Quit" << endl;
      cout << "Enter your choice:";
      cin >> choice;
      cin.get();
      switch(choice){
          case 1:
            	cout << "Enter your secret message:" << endl;
	        cin.getline(decrypted_message,50);
	        for (size_t i = 0; i < strlen(decrypted_message); ++i)
	          for (size_t j = 0; j < strlen(alphabets); ++j) 
	            {
	              if (alphabets[j] == decrypted_message[i])
	              {
	                encrypted_message[i] = key[j];
	                break;
	              }
	            }
	        cout << "The encrypted message is : " <<  encrypted_message << endl;
	        break;
        case 2:
        	cout << "Enter your secret message:" << endl;
	       cin.getline (encrypted_message,45);
	       for (size_t i = 0; i < strlen(encrypted_message); ++i)
	                for (size_t j = 0; j < strlen(key); ++j) 
	                    if (key[j] == encrypted_message[i])
	                    {
	                      decrypted_message[i] = alphabets[j];
	                      break;
	                    }
	        cout <<"The decrypted message is:" << decrypted_message << endl;
	        break;
        case 3:
        	cout << "Goodbye..." << endl;
        	break;
        default:
        	cout << " Invalid choice try again.";
      }

    } while(choice!= 3);        
        
    return 0;
}