C#

private const string c_EventSource = "TaskVision";
private const string c_LogName = "Application";

public static void Write(string errorMessage)
{
    try
    {
        //The event source should be created during installation
        if (EventLog.SourceExists(c_EventSource))
        {
            //Write the message as an error
            EventLog msg = new EventLog(c_LogName);
            msg.Source = c_EventSource;
            msg.WriteEntry(errorMessage);
        }
        else
        {
            //Try to create the event source for the next error. This requires admin rights.
            EventLog.CreateEventSource(c_EventSource, c_LogName);
        }
    }
    catch
    { }
}

onTextChanged()
{
   if (characterEntered != Digit)
   {
      Remove(lastCharacter);
   }
}