Delegates in C# with Example

Delgates are a special type of function used in C#.These are type safe.Delegates are refrence type that holds the address or reference to a method. By using delegate we can pass function as a parameter. C# delegates are similar to function pointer in C++.Delegates are especially used for implementing events and the call-back methods. All delegates are implicitly derived from the System.Delegate class.
Delegates can be chained together; for example, multiple methods can be called on a single event.

Basic syntax for delegate declaration

delegate <return type> <delegate-name> <parameter list>

Steps for working with delegate:

Declare delegate type

public delegate void printMessage(string str);

  
 Here i declare a delegate which has void return type and takes 1 string type of parameter. Means we can pass reference of a method who takes the same return type and arguments like delegate.

Create object of Delegate

printMessage objDel=new printMessage(Your_Function_Name);

 In this step i create delegate object by using new keyword and main thing to understand we have to pass method as a parameter at the time of delegate object creation.

Call delegate

objDel("Your_Message");

Here is the close enough to understand delegate with a simple Example

public delegate void printMessage(string str);

protected void Page_Load(object sender, EventArgs e)

{

   

       printMessage objDel=new printMessage(MyMessage);

        objDel("Delegate Successfully Called ");

}

public void MyMessage(string Message)

{

    lblMessage.Text = Message

}

Multicast Delegate

A Multicast Delegate holds the reference of more than one method. But we can only call those methods who having the same return type like delgate otherwise  there is a run-time exception.

We can add multiple methods in single delegate object using  '+'  operator and remove using  '-' operator.
Example:

protected void Page_Load(object sender, EventArgs e)

{

   MyDelegate myDel = new MyDelegate(AddNumbers);

        myDel += new MyDelegate(MultiplyNumbers);

        myDel(10, 20);

}

   public void AddNumbers(int x, int y)

    {

        int sum = x + y;

        MessageBox.Show(sum.ToString());

    }

    public void MultiplyNumbers(int x, int y)

    {

        int mul = x * y;

        MessageBox.Show(mul.ToString());

    }