StramWriter

private void button1_Click(object sender, EventArgs e) {

	string data = "ABC中文字";

	System.IO.StreamWriter writer = 

		new System.IO.StreamWriter(@"c:\\temp\\lab2.txt");

	writer.WriteLine(data);

	writer.WriteLine("Line2");

	writer.WriteLine("Line3");

	writer.Close();

}
 
private void button2_Click(object sender, EventArgs e) {

	System.IO.StreamReader r = 

		new System.IO.StreamReader(@"c:\\temp\\lab2.txt");

	string fileContent = r.ReadToEnd();

	textBox1.Text = fileContent;

	r.Close();

}
 
private void button3_Click(object sender, EventArgs e) {

	System.IO.StreamReader r =

		new System.IO.StreamReader(@"c:\\temp\\lab2.txt");
 
	do {

		string line = r.ReadLine();

		textBox1.Text += $"{line}\\r\\n";

	} while (!r.EndOfStream);
 
	r.Close();

}	
 

application.doevents()

backgroundworker

		private void button1_Click(object sender, EventArgs e) {
			for (int i = 1; i <= 100000; i++) {
				label1.Text = i.ToString();
			}
		}

SIGNALR

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 Lab1030_BackgroundWorker {
	public partial class Form1 : Form {
		public Form1() {
			InitializeComponent();
		}
 
		private void button1_Click(object sender, EventArgs e) {
			for (int i = 1; i <= 1000; i++) {
				label1.Text = i.ToString();
				Application.DoEvents();
			}
		}
 
		private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e) {
			for (int i = 1; i <= 1000; i++) {
				if (backgroundWorker1.CancellationPending) {
					break;
				}
				label1.Text = i.ToString();
			}
		}
 
		private void button2_Click(object sender, EventArgs e) {
			backgroundWorker1.RunWorkerAsync();
			this.Text = DateTime.Now.ToString();
		}
 
		private void button3_Click(object sender, EventArgs e) {
			backgroundWorker1.CancelAsync();
		}
	}
}

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 Lab1030_BackgroundWorker {
	public partial class Form1 : Form {
		public Form1() {
			InitializeComponent();
		}
 
		private void button1_Click(object sender, EventArgs e) {
			for (int i = 1; i <= 1000; i++) {
				label1.Text = i.ToString();
				Application.DoEvents();
			}
		}
 
		private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e) {
			for (int i = 1; i <= 1000; i++) {
				if (backgroundWorker1.CancellationPending) {
					break;
				}
				label1.Text = i.ToString();
			}
		}
 
		private void button2_Click(object sender, EventArgs e) {
			backgroundWorker1.RunWorkerAsync();
			this.Text = DateTime.Now.ToString();
		}
 
		private void button3_Click(object sender, EventArgs e) {
			backgroundWorker1.CancelAsync();
		}
	}
}

1. 按鈕 1 的功能 (button1_Click)：

   private void button1_Click(object sender, EventArgs e) {
       for (int i = 1; i <= 1000; i++) {
           label1.Text = i.ToString();
           Application.DoEvents();
       }
   }
   
   

   • 當用戶點擊按鈕 1 時，會從 1 數到 1000，並將每個數字顯示在 label1 控制項上。
   • Application.DoEvents() 允許應用程序處理其他事件，這樣用戶界面不會凍結。但這種方式不推薦使用，因為可能會導致不必要的性能問題。

2. 背景工作 (backgroundWorker1_DoWork)：

   private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e) {
       for (int i = 1; i <= 1000; i++) {
           if (backgroundWorker1.CancellationPending) {
               break;
           }
           label1.Text = i.ToString();
       }
   }
   
   

   • 這是背景工作執行的方法。在這裡，同樣是從 1 數到 1000，並更新 label1 的文本。
   • 使用 backgroundWorker1.CancellationPending 檢查是否需要取消任務。

3. 按鈕 2 的功能 (button2_Click)：

   private void button2_Click(object sender, EventArgs e) {
       backgroundWorker1.RunWorkerAsync();
       this.Text = DateTime.Now.ToString();
   }
   
   

   • 當用戶點擊按鈕 2 時，會開始背景工作，並將當前的日期和時間顯示在表單的標題上。