Reprompt user after invalid input-c++ - c++

Question

I modified the original code and the first two invalid input prompts work fine. when I implement the same logic into this prompt to start a new game, my program will not recognize an invalid input, with any key entered it will start a new game.
void newGame()
{
char newGameChoice = 'a';
cout << "\n--------------------------------------------------------------------------------" << endl;
cout << "Press N to play a new game\n";
cout << "Press X to exit\n\n";
cout << "--------------------------------------------------------------------------------" << endl;
cin >> newGameChoice;
newGameChoice = toupper(newGameChoice);
if (newGameChoice == 'N');
{
char userIn = 'a';
char c = 'a';
game(userIn, c);
}
while (newGameChoice != 'N' || 'X')
{
cout << "--------------------------------------------------------------------------------";
cout << "\n Invalid input. Please try again.\n" << endl;
cout << "--------------------------------------------------------------------------------" << endl;
newGame();
}
}

Answer 1

Your problem is this:
if (begin != 'B');
{
...
cin >> begin;
begin = toupper(begin);
start(); <------
You're calling start() again, which will read yet another value into begin.
Please spend more time analyzing your code before posting for help, it will help you to grow as a developer much more.

Answer 2

while (newGameChoice != 'N' || 'X')
is equivalent to
while (newGameChoice != 'N' || 'X' != 0)
Maybe what you mean is
while (newGameChoice != 'N' || newGameChoice != 'X')
Edit:
The code is wrong, it has to be rewritten, here is a suggestion:
void newGame()
{
char newGameChoice = 'a';
while (true) {
while (true) {
cin >> newGameChoice;
newGameChoice = toupper(newGameChoice);
if (newGameChoice != 'X' && newGameChoice != 'N') {
// Wrong input print error message
} else {
break;
}
}
if (newGameChoice == 'X') {
return;
}
game('a', 'a');
}
}

Answer 3

Part of your problem is that your start() method isn't designed in the most logical way. Currently when an invalid input is given, you attempt to read in another input and call start() again. When you called start() for the second time it starts back at the beginning of the start() method with no knowledge of the previous input.
What you should do instead is use a while() loop when an invalid entry is given and don't continue until a proper input is entered.
void start()
{
...
//Get initial user input
while begin != 'B'
{
Keep getting input if wrong
}
game(userIn, c);
}