Three ways to leave your Exception

gistfile1.cs

class Program
{
	static void Main(string[] args)
	{
		// Output:
		//
		// Invalid operation: Could not find file 'C:\this doesnt exist.txt'.
		// Could not find file 'C:\this doesnt exist.txt'.
		// Could not find file 'C:\this doesnt exist.txt'.
		//
		try
		{
			ThrowTest.ThrowNew();
		}
		catch (Exception ex)
		{
			Console.WriteLine(ex.Message);
		}
		try
		{
			ThrowTest.Throw();
		}
		catch (Exception ex)
		{
			Console.WriteLine(ex.Message);
		}
		try
		{
			ThrowTest.ThrowEx();
		}
		catch (Exception ex)
		{
			Console.WriteLine(ex.Message);
		}
		Console.ReadLine();
	}
}

public class ThrowTest
{
	public static void ThrowNew()
	{
		try
		{
			File.OpenText(@"C:\this doesnt exist.txt");
		}
		catch (IOException ex)
		{
			// InnerException is null, and the stacktrace starts at ThrowNew()
			throw new InvalidOperationException("Invalid operation: " + ex.Message);
		}
	}
	public static void Throw()
	{
		try
		{
			File.OpenText(@"C:\this doesnt exist.txt");
		}
		catch (IOException ex)
		{
			// This maintains the entire stacktrace, so will include the chain that occured inside the Framework,
			// i.e. at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
			throw;
		}
	}
	public static void ThrowEx()
	{
		try
		{
			File.OpenText(@"C:\this doesnt exist.txt");
		}
		catch (IOException ex)
		{
			// InnerException is null, and the stacktrace starts at ThrowEx(). It's the least useful of the three.
			throw ex;
		}
	}
}