更新“快速更改"给用户的价值?

问题描述

我想显示一个进度条或任何反映我的变量i值的东西，例如通过数百万次循环进行循环:

I want to show a progess bar or any thing reflecting the value of the variable i of mine when looping it through millions of loops like this:

for(int i = 0;i<1000000;i++)
{
   //How to updating its value to the user?
}

放置在循环中的任何命令，例如"label1.Text= i.ToString()"都将不起作用.
您能告诉我如何实现吗?
非常感谢您！

Any commands like "label1.Text= i.ToString()" placed in the loop won''t work.
Could you please tell me how to achieve that?
Thank you very much!

推荐答案

int num = 1000000;
progressBar1.Maximum = num;
for (int i = 0; i < num; i++)
{
    progressBar1.Value = i;
}

如果像这样使用BackgroundWorker，也可以使用标签

Also you could use a label if you use a BackgroundWorker like so

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

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    int num = 1000000;
    for (int i = 0; i < num; i++)
    {
        UpdateLabel(i);
    }
}

private delegate void UpdateLabelCallback(int val);
private void UpdateLabel(int val)
{
    if (label1.InvokeRequired)
    {
        UpdateLabelCallback ulc = new UpdateLabelCallback(UpdateLabel);
        label1.Invoke(ulc, new object[] { val });
    }
    else
    {
        label1.Text = val.ToString();
    }
}

if (i % 100000 == 0 || i == 1000000 - 1) {
    label1.Text = i.ToString();
}

为了使它正常工作，您将必须在另一个线程中执行整个循环，然后必须在UI线程上执行label1.Text的分配(您可以在此处找到如何执行此操作:).

根据您的实际操作，更好的方法可能是每隔一定的时间间隔(例如，每秒)更新一次屏幕.您可以使用计时器来执行此操作.看起来像这样:

For that to work properly, you will have to execute the entire loop in a different thread and then the assignment of label1.Text will have to execute on the UI thread (you can find out how to do that here: Changing a WinForms Control on the ''UI'' Thread from another Thread).

Depending on exactly what you are doing, a better way is probably to update the screen on some interval (e.g., every second). You can do this with a timer. That would look something like this:

ThreadStart ts = new ThreadStart(delegate()
{
    int j = 0;
    bool done = false;
    ThreadStart invoker = null;
    invoker = new ThreadStart(delegate()
    {
        if (this.InvokeRequired)
        {
            Thread.Sleep(1000);
            this.Invoke(invoker);
        }
        else
        {
            if (done)
            {
                label1.Text = "Done";
            }
            else
            {
                label1.Text = "Progress: " + j.ToString();
                (new Thread(invoker)).Start();
            }
        }
    });
    (new Thread(invoker)).Start();
    for (int i = 0; i < 1000000000; i++)
    {
        j = (i * 3) / ((i * 3 == 0) ? 1 : i * 3) * i + i - i;
        j = i;
    }
    done = true;
});
(new Thread(ts)).Start();

有更好的实现方法(例如Windows Forms计时器)，但您明白了.

There are better ways of implementing that (e.g., a Windows Forms timer), but you get the idea.

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