How can i raised custom event permanently?

Question

using System;
using System.IO;
public class FileSizeWarningEventArgs : EventArgs
private readonly string _filePath;
private readonly decimal _fileSize;
public FileSizeWarningEventArgs(FileInfo file)
_filePath = file.FullName;
_fileSize = file.Length;
public string FilePath
get { return _filePath; }
public decimal FileSize
get { return _fileSize; }
public delegate void FileSizeWarningEventHandler(object sender, FileSizeWarningEventArgs e);
public class FileSizeMonitor
private event FileSizeWarningEventHandler _fileSizeWarning;
private readonly decimal _thresholdSizeInByte;
private readonly FileInfo _file;
public FileSizeWarningEventHandler FileSizeWarning
get { return _fileSizeWarning; }
set { _fileSizeWarning = value; }
public FileSizeMonitor(string filePathToMonitor)
_thresholdSizeInByte = 500;
try
_file = new FileInfo(filePathToMonitor);
catch (Exception ex)
Console.WriteLine("Exception occurred! Message: {0}", ex.Message);
public void CheckFileSize()
if (_file != null && _file.Length > _thresholdSizeInByte)
OnFileSizeWarning(new FileSizeWarningEventArgs(_file));
protected void OnFileSizeWarning(FileSizeWarningEventArgs e)
if (_fileSizeWarning != null)
_fileSizeWarning(this, e);
class Program
static void Main()
var file1 = new FileSizeMonitor("C:\\1.txt");
file1.FileSizeWarning += file1__fileSizeWarning;
file1.CheckFileSize();
public static void file1__fileSizeWarning(object sender, FileSizeWarningEventArgs e)
Console.WriteLine("The File Size is larger than threshold, Current File Size: {0}Byte", e.FileSize);
how can i change above code to raise event whenever file size has been larger than threshold?
what is advantage of Event when I can use following code instead? 
using System;
using System.IO;
public class FileSizeMonitor
private readonly decimal _thresholdSizeInByte;
private readonly FileInfo _file;
public FileSizeMonitor(string filePathToMonitor)
_thresholdSizeInByte = 500;
try
_file = new FileInfo(filePathToMonitor);
catch (Exception ex)
Console.WriteLine("Exception occurred! Message: {0}", ex.Message);
public void CheckFileSize()
if (_file != null && _file.Length > _thresholdSizeInByte)
Console.WriteLine("The File Size is larger than threshold, Current File Size: {0}Byte", e.FileSize);
class Program
static void Main()
var file1 = new FileSizeMonitor("C:\\1.txt");
file1.CheckFileSize();
thank you/.

Answer 1

Hi, if your files keeps growing in size...you can add a  thread, may be with background priority, in your first code which will check size of file at some interval and if at any instance it found it larger than the limit it will raise the event
which can be used to show error message.
Here is a your modified code...
using System;
using System.IO;
using System.Threading;
namespace SimpleUI
    publicclassFileSizeWarningEventArgs : EventArgs
        privatereadonlystring _filePath;
        privatereadonlydecimal _fileSize;
        public FileSizeWarningEventArgs(FileInfo file)
            _filePath = file.FullName;
            _fileSize = file.Length;
        publicstring FilePath
            get { return _filePath; }
        publicdecimal FileSize
            get { return _fileSize; }
    publicdelegatevoidFileSizeWarningEventHandler(object sender, FileSizeWarningEventArgs e);
    publicclassFileSizeMonitor
        publiceventFileSizeWarningEventHandler FileSizeWarning;
        privatereadonlydecimal _thresholdSizeInByte;
        privatereadonlyThread _demonThread;
        privatereadonlystring _filePathToMonitor;
        public FileSizeMonitor(string filePathToMonitor, decimal threshold)
            _filePathToMonitor
                = filePathToMonitor;
            _thresholdSizeInByte
                = threshold;
            _demonThread
                = newThread(CheckFileSizeDemon);
        publicvoid Start()
            if (!_demonThread.IsAlive)
                _demonThread.Start();
        publicvoid CheckFileSizeDemon()
            try
while (true)
                    var _file = new FileInfo(_filePathToMonitor);
                    if (_file != null && _file.Length > _thresholdSizeInByte)
                        OnFileSizeWarning(new FileSizeWarningEventArgs(_file));
                    Thread.Sleep(10000);
            catch (Exception ex)
                Console.WriteLine("Exception occurred! Message: {0}", ex.Message);
        protectedvoid OnFileSizeWarning(FileSizeWarningEventArgs e)
            if (FileSizeWarning != null)
                FileSizeWarning(this, e);
    internalclassProgram
        privatestaticvoid Main1()
            var file1
                = newFileSizeMonitor("C:\\1.txt", 500);
            file1.FileSizeWarning
                += file1__fileSizeWarning;
            file1.Start();
        publicstaticvoid file1__fileSizeWarning(object sender, FileSizeWarningEventArgs e)
            Console.WriteLine("The File Size is larger than threshold, Current File Size: {0}Byte", e.FileSize);