Find File Content Using the .NET IO Class

Environment: C#, Win9x/2000/XP

This is a very simple application that uses the .NET I/O class to search the files' content in a directory. I first used a DirectoryInfo class to get the directory information. Then, I saved the file list in a FileInfo array. You loop through the array and open each file for reading. Convert the buffer to string type, find the text, and raise an event when it's found.

The searching process can be time consuming. We can use the .NET delegate function to search asynchronously, as show below.

//declare a delegate function
private delegate void FindAsyn();

static void Main(string[] args)

  FileFind ff = new FileFind();

  //subscribe the found file event
  ff.OnFileFound += new FoundDelegate(OnFoundFile);

  //The directory to be searched
  ff.PathName = @"C:\MyFileDir";
  //The text to be searched
  ff.FindText ="findtext";

  //delegate to...
  FindAsyn f = new FindAsyn(ff.StartSearch);
  //invoke the searching function asynchronously
  Console.Read();             // pause the screen;
  FileFind.bStopIt = true;    // stop it if the process takes
                              // too long.
  //unsubscribe the event
  ff.OnFileFound -= new FoundDelegate(OnFoundFile);


private static void OnFoundFile(string filename)


Download demo project - 7 Kb
Download source - 3 Kb


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