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c# - What is Action<string>?

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

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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


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