Question

i am working on simple application which select the file and read that text file and i want to delete all lines which start with `#comments line and here is code

 private void button1_Click(object sender, EventArgs e)
        {
            try
            {

                OpenFileDialog fdlg = new OpenFileDialog();
                fdlg.Title = ".txt File Detector";
                fdlg.InitialDirectory = @"c:\";
                fdlg.Filter = "txt files (*.txt)|*.txt";
                fdlg.FilterIndex = 2;
                fdlg.RestoreDirectory = true;
                if (fdlg.ShowDialog() == DialogResult.OK)
                {
                    input = fdlg.FileName;
                    textBox1.Text = fdlg.FileName;
                }
            }
            catch (Exception eee)
            {
                MessageBox.Show(eee.ToString());
            }
            string taxt = File.ReadAllText(input);
            string[] lines = new string[100000];
            //string taxt = File.ReadAllText(input);
          while(  taxt != null)
            {

            int count = 0;

                if (taxt.Trim().StartsWith("#") != true)
                {

                    lines[count] = taxt;
                    richTextBox1.Text += lines.ToString();
                    count++;
                }        


            }

i also tried to do with Regular expression as delimeter but that doesn’t work where regex for comments line which start with # is :

“@^#”
and after removing these comments line i want to store in arraylist

Answer 1

Your code has a number of problems:

• You’re reading the whole file into a single string, so you’re not actually looping over lines
• You’re looping while taxt is non-null, but never changing its value
• You’re calling string[].ToString on each iteration, for no obvious reason

You want something like:

richTextBox1.Lines = File.ReadLines(input)
                         .Where(line => !line.TrimStart().StartsWith("#"))
                         .ToArray();

However, you shouldn’t be doing the file handling in the UI thread. Do you actually want to show the result in a RichTextBox, or was that just for debugging?