Simple Exception Logger

21 Apr

The following class is probably the world simplest text logger.
There are several ways to open a file and write texts into it but I used File.AppendAllText() method because by using this method, it is guaranteed that the file handle will be closed, even if exceptions are raised.

public static class Logger
	public static void Log(string message)
		File.AppendAllText("C:\\MyLogFile.txt", DateTime.Now.ToShortDateString() + " " + DateTime.Now.ToShortTimeString() + ":\t" + message + Environment.NewLine);

Using the Logger class:
By handling Application.ThreadException event in Program.cs , you can log every un-handled exception into a text file for further examination.

static void Main(string[] args)
	Application.ThreadException += new System.Threading.ThreadExceptionEventHandler(Application_ThreadException); //it must be before Application.Run

static void Application_ThreadException(object sender, System.Threading.ThreadExceptionEventArgs e)

4 Responses to “Simple Exception Logger”

  1. Sohail May 15, 2010 at 3:03 pm #

    Thanks, this tip saves me a lot of trouble.

  2. Ecko June 15, 2010 at 1:06 pm #

    thanks,.. very nice post

  3. test September 9, 2011 at 6:17 pm #

    files are exclusively locked in Windows once they are opened by a thread. your so-called logger will raise error if used in multiple threads.

  4. Jochen June 20, 2014 at 5:22 pm #

    Yes, “test” is right. When in a multi-threaded environment, the best way to avoid the log file being blocked is to delegate writing to the file to a single background-task (thread). Log entries are transferred to the background-thread using a queue. See here:

    How this can be done thread-safe in a single class.

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