How to monitor change in files in windows system in c# using filesystemwatcher

The below given code will help you monitor all .txt files inside a given folder. It will monitor all .txt file in the given folder and subfolders. For you , if you have to monitor all .txt files in "C" drive, then give the path for FileSystemWatcher accordingly and set the filter to "*.txt" (Filter = "*.txt";) and set IncludeSubdirectories = true. It will then fire method "Action" for the changes to any .txt files.

public static void Main(string[] arg)
{
    FileSystemWatcher watcher = new FileSystemWatcher(@"C:\testFolder")
                                    {
                                        IncludeSubdirectories = true,

                                        NotifyFilter = NotifyFilters.LastAccess |NotifyFilters.LastWrite | NotifyFilters.FileName | NotifyFilters.DirectoryName,

                                        Filter = "*.txt"
                                    };



    // Add event handlers.
    watcher.Changed += Action;
    watcher.Created += Action;
    watcher.Deleted += Action;
    watcher.Renamed += Action;

    // Begin watching.
    watcher.EnableRaisingEvents = true;

    Console.ReadLine();

}
public static void Action(object obj, FileSystemEventArgs fileInfo)
{
    Console.WriteLine(fileInfo.FullPath.ToString() + fileInfo.ChangeType);
}