Question

I have pasted some code from Jon Skeet’s C# In Depth site:

static void Main() {     // First build a list of actions     List<Action> actions = new List<Action>();     for (int counter = 0; counter < 10; counter++)     {         actions.Add(() => Console.WriteLine(counter));     }      // Then execute them     foreach (Action action in actions)     {         action();     } }  

http://csharpindepth.com/Articles/Chapter5/Closures.aspx

Notice the line:

actions.Add( ()

What does the () mean inside the brackets?

I have seen several examples of lambda expressions, delegates, the use of the Action object, etc but I have seen no explanation of this syntax. What does it do? Why is it needed?

Answer 1

This is shorthand for declaring a lambda expression which takes no arguments.

() => 42;  // Takes no arguments returns 42 x => 42;   // Takes 1 argument and returns 42 (x) => 42; // Identical to above