Delegate is a type which holds the method(s) reference in an object. It is also referred to as a type safe function pointer.
Multicast delegates must contain only methods that return
Advantages
- Encapsulating the method's call from caller
- Effective use of delegate improves the performance of application
- Used to call a method asynchronously
Example
public delegate int mydelegate(int delvar1,int delvar2)Note
- You can use delegates without parameters or with parameter list
- You should follow the same syntax as in the method
(If you are referring to the method with twointparameters andintreturn type, the delegate which you are declaring should be in the same format. This is why it is referred to as type safe function pointer.)
Sample Program using Delegate
public delegate double Delegate_Prod(int a,int b);
class Class1
{
static double fn_Prodvalues(int val1,int val2)
{
return val1*val2;
}
static void Main(string[] args)
{
//Creating the Delegate Instance
Delegate_Prod delObj = new Delegate_Prod(fn_Prodvalues);
Console.Write("Please Enter Values");
int v1 = Int32.Parse(Console.ReadLine());
int v2 = Int32.Parse(Console.ReadLine());
//use a delegate for processing
double res = delObj(v1,v2);
Console.WriteLine ("Result :"+res);
Console.ReadLine();
}
}
Multicast Delegate
What is Multicast Delegate?
It is a delegate which holds the reference of more than one method.Multicast delegates must contain only methods that return
void, else there is a run-time exception. Simple Program using Multicast Delegate
delegate void Delegate_Multicast(int x, int y);Class Class2
{
static void Method1(int x, int y)
{
Console.WriteLine("You r in Method 1");
}
static void Method2(int x, int y)
{
Console.WriteLine("You r in Method 2");
}
public static void <place w:st="on" />Main</place />()
{
Delegate_Multicast func = new Delegate_Multicast(Method1);
func += new Delegate_Multicast(Method2);
func(1,2); // Method1 and Method2 are called
func -= new Delegate_Multicast(Method1);
func(2,3); // Only Method2 is called
}
}
