C#

private void dataGrid_CellValueChanged(object sender, DataGridViewCellEventArgs e) {
     /*check Changing cell is "not" in the "Total" Column,
      *would keep calling cell changed event, when the "Total" cell value changes*/
     if ((e.RowIndex >= 0) && e.ColumnIndex != DataGrid.Columns["Total"].Index) {
          //r = row of the changed Cell.
          int r = e.RowIndex;

          //get values from cells in the same row
          int Qty = 0;
          int.TryParse((string)DataGrid["Quantity", r].Value, out Qty);

          double Price = 0D;
          double.TryParse((string)DataGrid["UnitPrice", r].Value, out Price);

          //Calculate Total, Change cell value in "Total"
          DataGrid["Total", r].Value = Price * Qty;
     }
}

Arjun Mourya wrote:

So I want to read one complete line even if the file is read in chunks.

Bastard Programmer from Hell
If you can't read my code, try converting it here[^]

const string dataFile = @"F:\Bharath CS\Document1.txt"; 
       
        public Form1()
        {
            InitializeComponent();
            InitializeBackgroundWorker();
        }

        private void InitializeBackgroundWorker()
        {
            backgroundWorker1.DoWork +=
                new DoWorkEventHandler(backgroundWorker1_DoWork);
            backgroundWorker1.RunWorkerCompleted +=
                new RunWorkerCompletedEventHandler(
            backgroundWorker1_RunWorkerCompleted);
            backgroundWorker1.ProgressChanged +=
                new ProgressChangedEventHandler(
            backgroundWorker1_ProgressChanged_1);
        }

        private void button1_Click(object sender, EventArgs e)
        {
            
            backgroundWorker1.RunWorkerAsync();//300 gives a total of 3 seconds pause
        }

        private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
        {
            
            int count = 0;
            string prev = "";
            foreach (string line in File.ReadLines(dataFile))
            {
                
                
                if (backgroundWorker1.CancellationPending)//checks for cancel request
                {
                    //e.Cancel = true;
                    break;
                }
                backgroundWorker1.ReportProgress(count);//reports a percentage between 0 and 100
                try
                {
                    MySqlConnection conn1 = new MySqlConnection("server=demo;port=1234;database=demodb;userid=xyz;pwd=xyz");
                    conn1.Open();
                    MySqlCommand cmd1 = new MySqlCommand();
                    cmd1.Connection = conn1;
                    
                    string s = line.Replace("\"", "");
                   
                    
                    if (s.Length > 0 && !(s.Contains("-")))
                    {
                        if (s.Contains("ED5."))
                        {
                            cmd1.CommandText = "insert into yashomati_demo values('" + s + "')";
                            cmd1.ExecuteNonQuery();
                            
                            s = "";
                            count++;
                        }
                        
                        cmd1.Dispose();
                        conn1.Close();
                        conn1.Dispose();
                    }

                }
                catch (Exception ex) { throw ex; }

                
            }
           
        }

        

        private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
	        {
	            if (e.Cancelled)//it doesn't matter if the BG worker ends normally, or gets cancelled,
	            {              //both cases RunWorkerCompleted is invoked, so we need to check what has happened
	                MessageBox.Show("You've cancelled the backgroundworker!");
	 
	            }
	            else
	            {
	                
                    progressBar1.Value = 100;
	                MessageBox.Show("Done");
                   
                   
	            }
	        }
        

        private void backgroundWorker1_ProgressChanged_1(object sender, ProgressChangedEventArgs e)
        {
            progressBar1.Value = e.ProgressPercentage;
            

        }

        private void button2_Click(object sender, EventArgs e)
        {
            backgroundWorker1.CancelAsync();//makes the backgroundworker stop
        }
            
    }

string[] lines = File.ReadAllLines(datafile);

string origPath = @"D:\Temp\MyHugeText.txt";
string inPath = @"D:\Temp\MyHugeTextIn.txt";
string notInPath = @"D:\Temp\MyHugeTextOut.txt";

var lines = File.ReadLines(origPath);
var isIn = lines.Where(l => l.Contains("raise"));
var notIn = lines.Except(isIn);
File.WriteAllLines(inPath, isIn);
File.WriteAllLines(notInPath, notIn);