如何使用C单击按钮来中止一个while循环＃

Question

我有一个使用while循环显示数字的函数，但是我想通过单击按钮使用c＃来随机变量值停止执行while循环。

例如：

private void FrqSent() 
{ 
    int i = 1; 
    while (i <= 5)  
    { 
     i = i + 1; 
    } 
} 

Answer 1

这里是你如何使用一个BackgroundWorker来完成你的任务，一个简单的例子：

public partial class Form1 : Form 
{ 
    private int i = 1; 

    public Form1() 
    { 
     InitializeComponent(); 
    } 

    private void FrqSent() 
    {   
     while (i <= 500000000) 
     { 
      if (backgroundWorker1.CancellationPending) 
      { 
       break; 
      } 
      else 
      { 
       i = i + 1; 
      } 
     } 
    } 

    private void button1_Click(object sender, EventArgs e) 
    { 
     backgroundWorker1.RunWorkerAsync(); 
    } 

    private void button2_Click(object sender, EventArgs e) 
    { 
     backgroundWorker1.CancelAsync(); 
    } 

    private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e) 
    { 
     FrqSent(); 
    } 

    private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) 
    { 
     MessageBox.Show(i.ToString()); 
    } 
} 

只需创建一个新的Windows窗体项目，并添加一个BackgroundWorker对象和2个按钮。您必须手动设置DoWork，RunWorkerCompleted和Click事件。

编辑：不要忘记将BackgroundWorker的WorkerSupportsCancellation属性设置为true。

Answer 2

不是很优雅，但简单

public partial class Form1 : Form 
{ 
    private bool _stop; 

    public Form1() 
    { 
     InitializeComponent(); 
    } 

    private void buttonStart_Click(object sender, EventArgs e) 
    { 
     _stop = false; 
     FrqSent(); 
    } 

    private void buttonStop_Click(object sender, EventArgs e) 
    { 
     _stop = true; 
    } 

    private void FrqSent() 
    { 
     int i = 1; 
     while (i <= 5000000 && !_stop) 
     { 
      i = i + 1; 
      Application.DoEvents(); 
     } 
    } 

}