replace and delete some words from a file

Ultimately, the best way to approach this really depends on the length of you file and how efficient you want to be. All of the solutions mentioned will get the job done. Using regular expressions is probably faster than using String and Text builder objects. The problem with regular expressions is that they look a little archaic. Using System.Text.RegularExpressions; string myTxtFileStr = @"This is my input string: C:\temp\myFile.txt" string pttrnToFindStr = @"\Btion\s" // word ending in 'tion' string replacementStr = "sion" //finds all words ending in 'tion' and replaces 'tion' with 'sion' Regex.Replace(myTxtFileStr, pttrnToFindStr, replacementStr); There are also other things you can do to speed up the process for very large files. Multi-threaded designs using multiple buffer streams. Using multiple buffer streams and multiple threads (along with asynchronus reads), I could open a 100 MB text file and replace every instance of my intials T.A.D. with my name Thomas A Degen in about 10 to 15 seconds. Trying something like that using string builder would take substantially longer. However, doing the same process with a 5 K file might actually take LONGER to do it multi-threaded because there is so much overhead creating threads and buffers and such.

StringBuilder datatype will be smarter for operations with long texts.

I slightly easier way might be to: 1 - load the file into a string 2 - strMyString = strMyString.Replace("OldValue", "NewValue" ); 3 - write the string back out to a file if the file is too big, do it a line at a time. Cheers.

Hi, This is very simple . Open the file for what you want to replace and delete. Let us assume that you want replace a four letter word from that file. Take the first four alphabets compare that one with the word for want you want to replace, if matches? Replace that one, else leaving the first alphabet(ie starting from the second alphabet) take the next four alphabets and compare, go on like this till the end of the file and finish it. If matches, replace that one with the word what u want and then start taking next four alphabet from the end of the 4th alphabet of what you replaced. The same thing can be also done for deletion.... Have a source file and a destination file do the replacement and deletion in the destination file and atlast delete the source file and rename the destination file with the source file name. Thanks edward prakash