Question

I have a game where the user needs to enter x and y coordinates within a certain range, one at a time. Right now my input code is as follows:

do {
    printf("\n");
    cout << "X: ";
    cin >> x;
    cout << "Y: ";
    cin >> y;
} while (cin.fail());

I’m new to c++ but reading documentation lead me to believe this was an acceptable method for verifying user input. It works perfectly when the input is valid, however when the input is of a different type (for instance entering “a”) it infinitely loops with “X: Y: “. What do I need to do differently to have it wait for user input as if the lines were being read for the first time?

Answer 1

The biggest problem with trying to parse per variable is that when a user makes a mistake, their whole input becomes suspect.

Consider if I skip invalid input and enter: “3e4 40”. I meant “34 40”, but skipping the e might make “3 4” and leave “40” for later or might leave “4 40”.

Consider using getline to read a whole line in and parsing it such as with istringstream just as you are now — any error becomes an error without leaving the inputstream in a weird state.