String Array Is Populated But String Is Empty?

[AndreLouis]

My code is found at https://repl.it/@AndreLouis/caesarsCipher#main.cpp

My problem is on line 76, or the return value of caesarsCipher, encrypted_message. When I call cout << encrypted_message[1] through encrypted_message[10], etc... all of the characters exist. But if I try cout << encrypted_message it prints a blank space.

How do I get my code to return the entire string?

[salem c]

Because I don't want to sign into a service just to edit your code.

/*
Julius Caesar protected his confidential information by encrypting it using a cipher. Caesar's cipher 
(check Resources tab for more info) shifts each letter by a number of letters. If the shift takes you 
past the end of the alphabet, just rotate back to the front of the alphabet. In the case of a rotation by 
3, w, x, y and z would map to z, a, b and c.

Create a function that takes a string s (text to be encrypted) and an integer k (the rotation factor). 
It should return an encrypted string.

caesarCipher("Always-Look-on-the-Bright-Side-of-Life", 5)
➞ "Fqbfdx-Qttp-ts-ymj-Gwnlmy-Xnij-tk-Qnkj"

caesarCipher("A friend in need is a friend indeed", 20)
➞ "U zlcyhx ch hyyx cm u zlcyhx chxyyx"
*/

#include <iostream>

//#include "caesarsCipher"


std::string caesarsCipher(std::string message, int shift){
  std::string encrypted_message;
  int loop_shift = shift;

  for(size_t i=0;i<=message.length();i++){
    loop_shift = shift;
    // Take each character c, sort it into ASCII capitals, ASCII lower case, or space / dash
    char c = message[i];
    //std::cout << c << std::endl;
    // If c is a capital letter
    if(c >= 65 && c <=90){
      //std::cout << "c is a capital " << c << std::endl;
      // If there is a wrap-around
      //std::cout << "before the do if loop shift was " << shift << " and c was " << c << std::endl;
      do{
        if(c + loop_shift > 90){
        //std::cout << "Inside the uppercase while loop because the sum is ";
        //std::cout << c + shift << " which is greater than 90" << std::endl;
        // Reduce the shift by the remaining amount between c and the end of the alphabet
        loop_shift = loop_shift - (90 - c) - 1;
        //std::cout << "Now the shift is " << shift << std::endl;
        // Reset c to base value, A
        c = char(65);
        }
      }
      while(c + loop_shift > 90);
      //std::cout << "after the do if loop shift is " << shift << " and c is " << c << std::endl;
      encrypted_message += char(c + loop_shift);
    }
    // If c is a lowercase letter
    else if(c >= 97 && c <=122){
      //std::cout << "c is a lowercase " << c << std::endl;
      // If there is a wrap-around
      //std::cout << "before the do if loop shift was " << shift << " and c was " << c << std::endl;
      do{
        if(c + loop_shift > 122){
        //std::cout << "Inside the lowercase while loop because the sum is ";
        //std::cout << c + shift << " which is greater than 122" << std::endl;
        // Reduce the shift by the remaining amount between c and the end of the alphabet
        loop_shift = loop_shift - (122 - c) - 1;
        //std::cout << "Now the shift is " << shift << std::endl;
        // Reset c to base value, A
        c = char(97);
        }
      }
      while(c + loop_shift > 122);
      //std::cout << "after the do if loop shift is " << shift << " and c is " << c << std::endl;
    encrypted_message += char(c + loop_shift);
    }
    else{
      encrypted_message += c;
    }
  //std::cout << "c is " << int(c) << "\tshift is " << shift;
  //std::cout << "\tTheir sum is " << c + shift << std::endl;
  //std::cout << "The character that creates is " << char(c+shift) << std::endl;
  //std::cout << "The encrypted sequence is " << encrypted_message[i] << std::endl;
  }
  std::cout << encrypted_message[1];
  return encrypted_message;
}

int main(){
  std::string message_in;
  int shift_in;
  
  shift_in = 5;
  message_in = "Always-Look-on-the-Bright-Side-of-Life";
  //message_in = "Always-L";
  std::string encryption = caesarsCipher(message_in, shift_in);
  std::cout << encryption << std::endl;
}

The problem was your encrypted_message[i] only works if you arrange to reserve sufficient space when you first declare the string.

Other fixes
> if(c >= 65 && c <=90){
Say this for readability.
if(c >= 'A' && c <='Z'){

Or better (in #include <cctype> )
if( isupper(c) ){

[AndreLouis]

Hi Salem.

Thank you for going to the trouble to copy my code and fix it. I really appreciate it!

That makes sense! If I had either made it a vector, not an array, or if I had just modified the original input string instead of making a new string this would have worked. So I learned that if I treat an undeclared string like a vector it won't throw an error. Thanks!