C# 5 in a Nutshell

1. What is delegate in C#?

A delegate is an object that knows how to call a method.
A delegate type defines the kind of method that delegate instances can call. Specifically,
it defines the method’s return type and its parameter types.

The followingdefines a delegate type called Transformer:
delegate int Transformer (int x);

Transformer is compatible with any method with an int return type and a single
int parameter, such as this:
static int Square (int x) { return x * x; }
Assigning a method to a delegate variable creates a delegate instance:
Transformer t = Square;

complete code:

public delegate int Transformer (int x);

class Util

{

    public static void Transform (int[] values, Transformer t)

    {

        for (int i = ; i < values.Length; i++)

        values[i] = t (values[i]);

    }

}

class Test

{

    static void Main()

    {

        int[] values = { , ,  };

        Util.Transform (values, Square); // Hook in the Square method

        foreach (int i in values)

        Console.Write (i + " "); // 1 4 9

    }

    static int Square (int x) { return x * x; }

}

巴特西

C# 5 in a Nutshell - Delegate

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