Question

What is Action<string>, how can it be used?

Answer 1

Action is a standard delegate that has one to 4 parameters (16 in .NET 4) and doesn’t return value. It’s used to represent an action.

Action<String> print = (x) => Console.WriteLine(x);

List<String> names = new List<String> { "pierre", "paul", "jacques" };
names.ForEach(print);

There are other predefined delegates :

• Predicate, delegate that has one parameter and returns a boolean.

  Predicate<int> predicate = ((number) => number > 2);
  var list = new List<int> { 1, 1, 2, 3 };
  var newList = list.FindAll(predicate);
  

• Func is the more generic one, it has 1 to 4 parameters (16 in .NET 4) and returns something