Return to Revisions

Use TryParse() for retrieving integer input from the console. You can do this recursively and in far simpler terms using a ternary operator:

static int GetGCD(int x, int y)
{
    // if y is equal to 0, return x.
    // if y is not equal to 0, recursive call with x as y and y as the remainder.
    return y == 0 ? x : GetGCD(y, x % y);
}

Here we can use the method. Modular arithmetic should be positive. To ensure this, we use the absolute value of the input (Euclidean division).

static void Main()
{
    int x, y;
    
    // Get x. Ensure it's an integer.
    Console.WriteLine("Input first number: ");
    while(!Int32.TryParse(Console.ReadLine(), out x));
    
    // Get y. Ensure it's an integer.
    Console.WriteLine("Input second number: ");
    while(!Int32.TryParse(Console.ReadLine(), out y));

    // Ensure the values being used are positive.
    Console.WriteLine(GetGCD(Math.Abs(x), Math.Abs(y)));

    Console.ReadKey();
}