Delegates: Using Delegates

Delegate definition

is almost similar to method declarations.

Syntax

<accessmodifier> delegate <methoddeclaration>

Example

public delegate int Calc(int a, int b);

Delegate variable declaration

is just like variable declaration

Syntax

<delegatetype> <delegatevariable>

Example

Calc c;

Method assignment to delegates

To use a delegate, we have to associate a method to the delegate instance.
Method to be associated to a delegate should match the signature of the delegate, which includes parameter types and return types

Example

public int Add(int x, int y)
{
return x+y;
}

Instantiating delegates

Syntax

new <delegatetype>(<methodname>)

Example

Calc c= new Calc(Add);

Using a delegates

Delegates are basically used to invoke a method which is associated to it.
.Net automatically adds few methods to it which enables us to invoke the method.

Here Invoke(int a, int b) will be added to Calc delegate.
Methods associated with the delegates can be invoked using the following syntax

Syntax

<delegatevariable>.Invoke(<parameters>)

Example

int x = c.invoke(10, 20);

There is another simple shortcut for this.
Syntax

<delegatevariable>(<parameters>)

Example

int x = c(10, 20);