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I am using the below code to practice FileSystemWatcher.Changed Event from here. It perfectly works fine with .txt extension, but the output is not as I expect to see when I use .pdf. It triggers one "Created" events and multiple "Changed" events.

using System;
using System.IO;
using System.Security.Permissions;

public class Watcher
{

    public static void Main()
    {
        Run();

    }

    [PermissionSet(SecurityAction.Demand, Name = "FullTrust")]
    public static void Run()
    {
        string[] args = System.Environment.GetCommandLineArgs();

        // If a directory is not specified, exit program.
        if (args.Length != 2)
        {
            // Display the proper way to call the program.
            Console.WriteLine("Usage: Watcher.exe (directory)");
            return;
        }

        // Create a new FileSystemWatcher and set its properties.
        FileSystemWatcher watcher = new FileSystemWatcher();
        watcher.Path = args[1];
        /* Watch for changes in LastAccess and LastWrite times, and
           the renaming of files or directories. */
        watcher.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite
           | NotifyFilters.FileName | NotifyFilters.DirectoryName;
        // Only watch text files.
        watcher.Filter = "*.pdf";

        // Add event handlers.
        watcher.Changed += new FileSystemEventHandler(OnChanged);
        watcher.Created += new FileSystemEventHandler(OnChanged);
        watcher.Deleted += new FileSystemEventHandler(OnChanged);
        watcher.Renamed += new RenamedEventHandler(OnRenamed);

        // Begin watching.
        watcher.EnableRaisingEvents = true;

        // Wait for the user to quit the program.
        Console.WriteLine("Press \'q\' to quit the sample.");
        while (Console.Read() != 'q') ;
    }

    // Define the event handlers.
    private static void OnChanged(object source, FileSystemEventArgs e)
    {
        // Specify what is done when a file is changed, created, or deleted.
        Console.WriteLine("File: " + e.FullPath + " " + e.ChangeType);
    }

    private static void OnRenamed(object source, RenamedEventArgs e)
    {
        // Specify what is done when a file is renamed.
        Console.WriteLine("File: {0} renamed to {1}", e.OldFullPath, e.FullPath);
    }
}

Here is the output when I copy a PDF file to watching folder:

File: c:\test\innovation.pdf Created
File: c:\test\innovation.pdf Changed
File: c:\test\innovation.pdf Changed
File: c:\test\innovation.pdf Changed
File: c:\test\innovation.pdf Changed

Any idea why that happens?

mazkopolo
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  • because the filesize/attributes change whilst copying the file over. https://msdn.microsoft.com/en-us/library/system.io.filesystemwatcher.onchanged(v=vs.110).aspx - as per the docs, use the NotifyFilter property to restrict the number of events raised – Ahmed ilyas Nov 30 '15 at 02:34

1 Answers1

1

Thanks to Ahmed Ilyas. All I needed to do was to change:

watcher.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite
       | NotifyFilters.FileName | NotifyFilters.DirectoryName;

to

watcher.NotifyFilter = NotifyFilters.FileName;
mazkopolo
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