Making a display menu and asking user to choose one and error check to keep asking until one of the three are chosen

[ccaudle]

Im trying to make it where you choose either 1,2, or 3 and if you don't choose one of those then it will repeat and ask you to try again basically.
Im unsure if I need to do just a while loop or not to make this work out.


char start_game ()
{
char choice;
cout <<" 1) New Game 2) Load Game 3) Quit\n"
do
{
cout << "Enter 1,2, or 3:\n"
cin >> choice

while (choice != '1' && choice != '2' && choice! = '3')
}
return choice;
}

[dhayden]

Getting and validating user input is an example of a loop where the exit condition is in the middle of the loop. You'll find that the code is much cleaner if you write it that way rather than trying shoe-horn it into a traditional loop.

#include <iostream>

using std::cin;
using std::cout;

// Prompt the user for an integer value using "prompt".
// Validate that the choice is in the range [low, high].
// Reprompt if they enter a non-number or invalid value
int getChoice(const char *prompt, int low, int high)
{
    int result;
    while (true) {
	cout << prompt;
	if (cin >> result) {
	    if (low <= result && result <= high) {
		return result;
	    } else {
		cout << "The value must be between " << low
		     << " and " << high << '\n';
	    }
	} else {
	    // non-number entered
	    cout << "That isn't a number\n";
	    cin.clear();	// clear the error
	    cin.ignore(1000000, '\n'); // skip to end of line
	}
    }
}

int
main()
{
    cout << " 1) New Game 2)Load Game 3) Quit\n";
    int choice = getChoice("Enter 1,2, or 3:\n", 1, 3);
    cout << "You choose " << choice;
    return 0;
}

 1) New Game 2)Load Game 3) Quit
Enter 1,2, or 3:
4
The value must be between 1 and 3
Enter 1,2, or 3:
0
The value must be between 1 and 3
Enter 1,2, or 3:
four
That isn't a number
Enter 1,2, or 3:
3
You choose 3