mscorlib.dll中的错误“ System.StackOverflowException”

Question

How to solve this error?

This is my code

public void X()
{
    foreach (char c in txtNumbers.Text)
    {
        sum = sum + (int.Parse(c.ToString()) * int.Parse(c.ToString()));
    }

    txtNumbers.Text = (sum.ToString());
    sum = 0;

    if (txtNumbers.Text == "1")
    {
        Response.Write("happy numbers");
        return;
    } else { 
        X();
    }
}

And this is the error...

Answer 1

if the numbers don't add up to "1", your program is going to enter into an infinite loop. and crash. hard. like it did.

This is because in your else block, you call X() method again. And there seems to be no way to stop your recursion and hence your program is crashing.

A simple fix:

public void X()
{
        foreach (char c in txtNumbers.Text)
        {
            sum = sum + (int.Parse(c.ToString()) * int.Parse(c.ToString()));
        }

        txtNumbers.Text = (sum.ToString());
        sum = 0;

        if (txtNumbers.Text == "1")
        {
            Response.Write("happy numbers");
            return;
        }else{
             Response.Write("sad numbers");
        }
    }

Also, I recommend using TryParse() methods, but that's for another season.

Answer 2

I believe the error is that the X method recursively calls itself. This is the root cause of the stack overflow but it is actually getting triggered on the int.Parse call. You need to change your else logic so that it doesn't keep branching into X() without ever terminating

Answer 3

If txtNumbers.Text is never "1" you will have a recursion that continues until you get the StackOverflowException. Simply because you invoke X() when txtNumbers.Text is different from "1" .