Copying newlines between files in C++

I'm new to this forum as well as C++ in general, and I'm making a program that imports text from one file, changes it a bit, and then moves the changed text over to another file. Anyways, I didn't have much of a problem changing the text over, but the way that I tried to bring the newlines over didn't work, and I have no idea why. Thanks. I could really use some help.

    char fileChars;
    ifstream codedMessage; 
    ofstream decodedMessage;

    cout << "Decoding File" << endl;

    codedMessage.open("secretMessage.txt");
    decodedMessage.open("decipheredMessage.txt"); 

    if (codedMessage.fail() ) {
           cerr << "Error..." << endl;
           exit(1);
    }

    while (!codedMessage.eof()){ 
      codedMessage >> fileChars;
      if (fileChars == '\n') {
        decodedMessage << "\n";
      } else if (fileChars == '~') {
        decodedMessage << ' ';
      } else {
        decodedMessage << ++fileChars;
      }
    }

    cout << "Closing Files." << endl;
    codedMessage.close(); 
    decodedMessage.close();