C# (Windows Forms Application) Using While loop

Question

Hey guys. I started to study C# (Windows Forms Application) in Visual Studio 2010.
This is the Task I need to do but I have no idea how to do it. I have spent hours on this task but I failed at it. I looked on internet for help but I haven't found anything that would help me with the task, so if any of you could help me with this task I would really appreciate it.
It really matters for me a lot because I did 2 star task easily but I want to submit every 3 star task.

Vulpes · Answer

Try this: private void button1_Click(object sender EventArgs e) { int number; bool isValid = int.TryParse(textBox1.Text out number); if (!isValid || number { MessageBox.Show(Please enter a valid positive integer in the textbox); textBox1.Focus(); return; } int sum = 0; int i = 0; while (i { sum += i; i++; } MessageBox.Show(Sum is  + sum); }

Mineten · Answer

It's working. Thank you very much :)