Chapter 13, Problem 3AW

Program Plan Intro

Declaration of delegate type in Question 1:

Suppose a class consists of the following method:

private void ShowValue(int i)

{

    MessageBox.Show(i.ToString());

}

Explanation:

In the above given statement,

• The return type is void.
• The method consists of one parameter, an integer.

If this method has to be assigned to a delegate, then a delegate must be used to call the method. Initially, a delegate type must be declared as follows:

//Declare delegate type

delegate void DisplayInteger(int i);

• The above statement declares a delegate type named DisplayInteger, that can reference any void method, which has one parameter, an integer.
• This declaration starts with the delegate keyword, followed by code, which is same as that of a method header, terminated with a semicolon.

Creation of an instance in Question 2:

In the above given case, the delegate type is declared, now an actual delegate has to be created.

The statement to create an instance of the delegate type is as follows:

DisplayInteger ShowIntValue = ShowValue;

The above given statement creates a delegate named ShowIntValue, and the ShowValue method is assigned to the delegate. A delegate can reference any method as long as it has a return type and parameter list matching that of the delegate type.