Program not responding after Button click

Question

I know it ain't pretty but i am still rather new at programming. After i input the n1, n2 and n3 and press calculate the form gets an "Program not responding"

it does so both in Debug and Release mode and i have no visible error messages.Anyone who can help me? it is for an assignment due tomorrow, and right now i cannot see a fix, so any help is much appreciated.

If you need a copy of the code to check, please send me a pm.

With kind regards. Mathias

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace I3_REVISI
{
    public partial class Newton : Form
{
    public static double n1, n2, n3, x_NEWTON, Initialization, x1, approx1, approx2, approx3, approx4, approx5, approx6;
    public Newton()
    {
        InitializeComponent();
    }

    private void button2_Click(object sender, EventArgs e)
    {
        Form1 f1 = new Form1();
        f1.Show();
        this.Hide();
    }

    private void label1_Click(object sender, EventArgs e)
    {

    }

    private void textBox4_TextChanged(object sender, EventArgs e)
    {

    }

    private void textBox8_TextChanged(object sender, EventArgs e)
    {

    }

    private void textBox7_TextChanged(object sender, EventArgs e)
    {

    }

    private void textBox11_TextChanged(object sender, EventArgs e)
    {

    }

    private void button1_Click(object sender, EventArgs e)
    {

        textBox6.Text = "";
        textBox10.Text = "";
        textBox13.Text = "";
        textBox3.Text = "";
        Newton1.Text = "";
    }

    private void button3_Click(object sender, EventArgs e)
    {
        n1 = Convert.ToDouble(textBox6.Text);
        n2 = Convert.ToDouble(textBox10.Text);
        n3 = Convert.ToDouble(textBox13.Text);
        // Initialization If value is positive the start value is xinitialization -1 f(0) = xinitialization-1

        for (x_NEWTON = 0; x1 >= 0; x_NEWTON++)
        {
            x1 = n1 * Math.Pow(x_NEWTON, 2) + n2 * x_NEWTON + n3;
            Initialization = x1 - 1;
        }

        // Formula:   x1 = x0 - ( f(x0) / f'(x0) )
            approx1 = Initialization - ((n1*Math.Pow(Initialization,2)+n2*Initialization+n3) / (n1*2*Initialization-n2));
        approx2 = approx1 - ((n1 * Math.Pow(approx1, 2) + n2 * approx1 + n3) / (n1 * 2 * approx1 - n2));
        approx3 = approx2 - ((n1 * Math.Pow(approx2, 2) + n2 * approx2 + n3) / (n1 * 2 * approx2 - n2));
        approx4 = approx3 - ((n1 * Math.Pow(approx3, 2) + n2 * approx3 + n3) / (n1 * 2 * approx3 - n2));
        approx5 = approx4 - ((n1 * Math.Pow(approx4, 2) + n2 * approx4 + n3) / (n1 * 2 * approx4 - n2));
        approx6 = approx5 - ((n1 * Math.Pow(approx5, 2) + n2 * approx5 + n3) / (n1 * 2 * approx5 - n2));

        Newton1.Text = ("" + approx6);

    }

    private void textBox1_TextChanged(object sender, EventArgs e)
    {

    }

    private void textBox10_TextChanged(object sender, EventArgs e)
    {

    }
}
}

Suspecting that for loop is running indefinitely. Use try catch for exception. It might throw stack overflow exception. x1 >= 0; — CodeConstruct, Nov 26 '18 at 05:14
Your for loop continues while `x1 >= 0`, is this ever false? If not, your loop will never end. I recommend taking a look at [using the debugger](https://stackoverflow.com/questions/25385173/what-is-a-debugger-and-how-can-it-help-me-diagnose-problems) — ProgrammingLlama, Nov 26 '18 at 05:15
@CodeConstruct it would never throw a StackOverflowException. -- Mathias a try/catch wouldn't do anything here. — ProgrammingLlama, Nov 26 '18 at 05:16
[Here's a tutorial on using the debugger in Visual Studio](https://tutorials.visualstudio.com/vs-get-started/debugging). — ProgrammingLlama, Nov 26 '18 at 05:16
@CodeConstruct also, `StackOverflowException` can't be catched in `try/catch` block. — vasily.sib, Nov 26 '18 at 05:17
You were right, it was the For loop.. But i don't understand why it continues to run, the break condition of bigger than 0 should be reached. Any suggestions on how to build it instead? — Mathias C. Andersen, Nov 26 '18 at 05:26
"the break condition of bigger than 0 should be reached" - that isn't a break condition, it's a continuation condition. See [C# `for` statement](https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/for#the-condition-section) — ProgrammingLlama, Nov 26 '18 at 05:26
As for a suggestion: if you thought that it was a break condition, just reverse the logic to make it correct: `i >= 0` becomes `i < 0`. — ProgrammingLlama, Nov 26 '18 at 05:30
If this is an assigment for tomorrow, than i suggest getting started with debugging. Putting your code here wont help you. You need to do some effort yourself first — GuidoG, Nov 26 '18 at 12:05

score 0 · Answer 1 · edited Nov 26 '18 at 06:10

check your input value datatype and prevent input string or value to cause crash your formula like division by zero
change your for loop index from value to less tan a value

for (int i =0 ; i<10)

and keep your code in try catch block and pass exception parameter to see your error.

try
{
    n1 = Convert.ToDouble(textBox6.Text);
    n2 = Convert.ToDouble(textBox10.Text);
    n3 = Convert.ToDouble(textBox13.Text);
    f(0) = xinitialization-1;

    for (x_NEWTON = 0; x1 >= 0; x_NEWTON++)
    {
        x1 = n1 * Math.Pow(x_NEWTON, 2) + n2 * x_NEWTON + n3;
        Initialization = x1 - 1;
    }

        approx1 = Initialization - ((n1*Math.Pow(Initialization,2)+n2*Initialization+n3) / (n1*2*Initialization-n2));
    approx2 = approx1 - ((n1 * Math.Pow(approx1, 2) + n2 * approx1 + n3) / (n1 * 2 * approx1 - n2));
    approx3 = approx2 - ((n1 * Math.Pow(approx2, 2) + n2 * approx2 + n3) / (n1 * 2 * approx2 - n2));
    approx4 = approx3 - ((n1 * Math.Pow(approx3, 2) + n2 * approx3 + n3) / (n1 * 2 * approx3 - n2));
    approx5 = approx4 - ((n1 * Math.Pow(approx4, 2) + n2 * approx4 + n3) / (n1 * 2 * approx4 - n2));
    approx6 = approx5 - ((n1 * Math.Pow(approx5, 2) + n2 * approx5 + n3) / (n1 * 2 * approx5 - n2));

    Newton1.Text = ("" + approx6);
}
catch (exception ex)
{
    messagebox.show(ex.message);
}

1. Checking user input is good (even though you are not checking it in your code sample), but this is definitely not the reason of infinite loop. 2. what is _tan_ value? you mean ten? But there maybe more then ten iterations required? 3. Putting `try/catch` everywhere is bad. — vasily.sib, Nov 26 '18 at 10:42
Also, as for now this looks more like a comment, than an answer. Can you improve it? — vasily.sib, Nov 26 '18 at 10:44

Program not responding after Button click

1 Answers1