Hi, I have a text file in which there are 10000 lines. There are 225 numerical values on each line and each numerical value is followed by a index number and a colon e.g., 1:0.021354 2:0.125432 3:451321 ...... 225:0.001254. Now I want to remove this indexing. I know how to add indexing but could not perform to remove that. Please help me in solving this problem. Thanks Here is the code for adding indexing. Code: static void Main(string[] args) { string[] files = Directory.GetFiles(@"F:\New folder", "*.txt", SearchOption.AllDirectories); StringBuilder strFile = new StringBuilder(); foreach (string file in files) { using (StreamReader sr = new StreamReader(file)) { string s = Path.ChangeExtension(file, null); strFile.AppendFormat(s.Substring(s.LastIndexOf(@"\") + 1) + " "); // string s = Path.GetFileName("-1"); // strFile.AppendFormat(s + " "); char[] charsToTrim = { ' ', '\r', '\n' }; string kkj = (sr.ReadToEnd().TrimEnd(charsToTrim)); string[] words = kkj.Split(' '); string temp = ""; int iCounter = 1; foreach (string word in words) { if (word.Contains("-0.000000")) { temp = word.Replace("-0.000000", ""); strFile.Append(temp); iCounter++; continue; } else if (word.Contains("0.000000")) { temp = word.Replace("0.000000", ""); strFile.Append(temp); iCounter++; continue; } strFile.Append(iCounter++ + ":" + word + " "); } strFile.AppendLine(); } } using (StreamWriter outfile = new StreamWriter(@"F:\New folder (3)\-1.train")) { outfile.Write(strFile.ToString()); } }