Example 3_5 while statement

Topic description 

Create a C# Windows application, enter n, and find 1+2+3+..+n.

Steps 

1> First add 2 Label controls, 1 TextBox, and 1 Button control to Windows Forms. The main property settings of each control are listed in the following table.

controls	Attributes	property settings	controls	Attributes	property settings
label1	Text	n:	textBox1	Name	txtNum
label2	Text	""	button	Name	btnOk
	Name	lbShow		Text	Sure

2> Double-click the "btnOk" button in the form design area, the system automatically adds the "Click" event and the corresponding event method for the button, and then edit the code in the source code view .

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

namespace Test3_5
{
    public partial class Test3_5 : Form
    {
        public Test3_5()
        {
            InitializeComponent();
        }

        private void btnOk_Click(object sender, EventArgs e)
        {
            int n = Convert.ToInt32(txtNum.Text);
            int i = 1;
            int sum=0;
            while(i<=n){
                sum+=i;
                i++;
            }
            lblShow.Text = "1+2+3+....+n = " + sum;
        }
    }
}