c# - 如何使用 foreach 终止和重新启动

Question

这里是我的代码，但是在stop = true之后，再次stop = false不会再循环

    bool stop = false;
    private void button1_Click(object sender, EventArgs e)
    {
        string filename = @"temp1.txt";
        int n = 5;
        foreach (var line in File.ReadLines(filename).AsParallel().WithDegreeOfParallelism(n))
        {
            textBox1.Text = line;

            if (stop == true)
            {
                break;
            }
            stop = false;
        }
    }

    private void button4_Click(object sender, EventArgs e)
    {
        stop = true;
    }

Answer 1

stop 永远不会在您的代码中重置为 false。每次单击 button1 时使用新的 CancellationToken 可能会更好:

private CancellationTokenSource cancellationTokenSource;

private void button1_Click(object sender, EventArgs e)
{
    // create a new CancellationTokenSource and Token for this event
    cancellationTokenSource = new CancellationTokenSource();
    var cancellationToken = cancellationTokenSource.Token;

    string filename = @"temp1.txt";
    int n = 5;
    foreach (var line in File.ReadLines(filename).AsParallel().WithDegreeOfParallelism(n))
    {
        textBox1.Text = line;

        // Check if token has had a requested cancellation.
        if (cancellationToken.IsCancellationRequested)
            break;
    }
}

private void button4_Click(object sender, EventArgs e)
{
    if (cancellationTokenSource != null)
        cancellationTokenSource.Cancel();
}