Exception

throw

if (aantal <= 0) 
    throw new ArgumentException(“Aantal moet groter zijn dan nul”);

try-catch-finally

System.IO.StreamWriter sw = null;
try
{
    sw = new System.IO.StreamWriter(@"C:\test\test.txt");
    sw.WriteLine("Hello");
}

catch (System.IO.FileNotFoundException ex)
{
    // Put the more specific exception first.
    System.Console.WriteLine(ex.ToString());  
}

catch (System.IO.IOException ex)
{
    // Put the less specific exception last.
    System.Console.WriteLine(ex.ToString());  
}
finally 
{
    sw.Close();
}

custom exception

[Serializable]
public class EmployeeListNotFoundException: Exception
{
    public EmployeeListNotFoundException()
    {
    }

    public EmployeeListNotFoundException(string message) : base(message)
    {
    }

    public EmployeeListNotFoundException(string message, Exception inner) : base(message, inner)
    {
    }
}

filters (voegt condities toe aan catch block)

try
{
    Foo.DoSomethingThatMightFail(null);
}
catch (MyException ex) when (ex.Code == 42)
{
    Console.WriteLine("Error 42 occurred");
}