Delegate is a user defined data type, it is used to
store the reference on method. C# delegate work same as c language pointer.
Use
of the delegate: Use of the delegate is that when you
have two or more methods with same name and same signature and call all the
method with single object.
The example of the delegate is given below:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace WindowsFormsApplication8
{
public delegate int mydel(int x, int y);
public class Class1
{
public int add(int a, int b)
{
return a + b;
}
public int sub(int a, int b)
{
return a - b;
}
}
}
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace WindowsFormsApplication8
{
public delegate int mydel(int x, int y);
public class Class1
{
public int add(int a, int b)
{
return a + b;
}
public int sub(int a, int b)
{
return a - b;
}
}
}
.cs code
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace WindowsFormsApplication8
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
Class1 obj = new Class1();
mydel del = obj.add;
int i = del(10, 20);
MessageBox.Show(i.ToString());
mydel del1 = obj.sub;
int j = del1(20, 10);
MessageBox.Show(j.ToString());
}
}
}
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace WindowsFormsApplication8
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
Class1 obj = new Class1();
mydel del = obj.add;
int i = del(10, 20);
MessageBox.Show(i.ToString());
mydel del1 = obj.sub;
int j = del1(20, 10);
MessageBox.Show(j.ToString());
}
}
}
Output :
30
10
Types
of delegate:
There are two types of delegate –
-Single cast delegates
-Multi cast delegates
Single
cast Delegate – single cast delegate hold the address
of single method like as explained in the above example.
Multicast
Delegate - multicast delegate is used to hold the address of
multiple methods, for this work we will use overloaded += operator and remove
the address from delegate we use overloaded operator -=
Multicast Delegates will work for those methods
which have return type only void.
The example of the Multicast delegates is given
below:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace WindowsFormsApplication9
{
public delegate void mydel(int a, int b);
public class Class1
{
public void add(int x, int y)
{
MessageBox.Show("addition
value"+(x+y).ToString());
}
public void sub(int x, int y)
{
MessageBox.Show("subtraction
value" + (x - y).ToString());
}
public void mul(int x, int y)
{
MessageBox.Show("multly
value" + (x * y).ToString());
}
}
}
.cs
code :
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace WindowsFormsApplication9
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void
button1_Click(object sender, EventArgs e)
{
Class1 obj = new Class1();
mydel del = Class1.add;
del += Class1.sub;
del += Class1.mul;
del(10, 5);
}
}
}
Output:
addition
value : 15
subtraction
value : 5
multiply
value : 50
