Question

I’m a beginner to C# & I’m using HttpWebRequest to obtain a web page source. Well I’m using regex to scan the source code for content inside the html element . Basically the regex looks like this in C#.

Match m = Regex.Match(result, @"^(.*?<form .*?>(.*?)</form>.*?)+$", RegexOptions.Singleline);

The only problem that i’m facing is that until this process is completed my application freezes. Will background threading help me ? if so could you please be kind to help me out with a snippet for implementing it ? .. It will be great if i can display a progress bar or something for the user.

private void button1_Click(object sender, EventArgs e) 
        {

            Thread backgroundThread = new Thread(
                new ThreadStart(() =>
                {
                    Match m = Regex.Match(result, @"^(.*?<form .*?>(.*?)</form>.*?)+$", RegexOptions.Singleline);

                    foreach (var capture in m.Groups[2].Captures)
                    {
                        forms.Add(capture.ToString());
                    }

                    MessageBox.Show("Thread completed!");

                    if (progressBar.InvokeRequired)
                        progressBar.BeginInvoke(new Action(() => progressBar1.Value = 0));
                }
            ));

            backgroundThread.Start();
        }

Answer 1

Here is some demonstration thread code using the System.Threading.Tasks;

Task<string> GetContent(string rawContent)
{
    var task = Task<string>.Factory.StartNew(ProcessContent, rawContent);
    return task;
}

string ProcessContent(object source)
{
    var input = (string)source;
    var match = Regex.Match(input, @"^(.*?<form .*?>(.*?)</form>.*?)+$", RegexOptions.Singleline);
    return match.Success ? match.Value : string.Empty;
}

Alternative syntax:

Task<string> GetContent(string rawContent)
{
    var rc = rawContent;
    var task = Task<string>.Factory.StartNew(() => 
    {
        var match = Regex.Match(rc, @"^(.*?<form .*?>(.*?)</form>.*?)+$", RegexOptions.Singleline);
        return match.Success ? match.Value : string.Empty;
    });
    return task;
}

Usage:

var content = await GetContent(myContent); // Where myContent is your content