This code is for io programming in sync and async modes

async-file-io.cs

string StartDirectory = @"D:\temp\source";
string EndDirectory = @"D:\temp\destination";

private async void btnStartAsync_Click(object sender, EventArgs e)
{
	foreach (string filename in Directory.EnumerateFiles(StartDirectory))
	{
		using (FileStream SourceStream = File.Open(filename, FileMode.Open))
		{
			var destFilePath = EndDirectory + filename.Substring(filename.LastIndexOf('\\'));
			using (FileStream DestinationStream = File.Create(destFilePath))
			{
				await SourceStream.CopyToAsync(DestinationStream);
			}
		}
	}
}

private void btnStartSync_Click(object sender, EventArgs e)
{
	foreach (string filename in Directory.EnumerateFiles(StartDirectory))
	{
		using (FileStream SourceStream = File.Open(filename, FileMode.Open))
		{
			using (FileStream DestinationStream = File.Create(EndDirectory + filename.Substring(filename.LastIndexOf('\\'))))
			{
				SourceStream.CopyTo(DestinationStream);
			}
		}
	}
}