Working with Delegates in C# .net
- Delegates holds the address of one function or addresses of many functions.
Delegates are divided in to two types :-
- Single cast Delegate
Multi cast delegate
- SCD holds the address of one function only.
- MCD allows to hold the address of many functions.
4.Steps to crates a Delegate :-
Step 1. Write a class with a method
Syntax :-
Class Test
{
Public void Print () {logic ;}
}
Step 2. Create a Delegate
Syntax :-
Public delegate void D name ();
- Keyword
- Delegate name
Step 3 . create an object for the delegate with the address of a method.
Syntax :-
Test t = new Test ()
D name d = new D name (t. print);
Step 4. Call the Delegate
Syntax :- d ();
Example on SCD :-
- Open console Application Project
- Code in GD (before Main ())
{
Class Test
{
Public void Print ()
{
Console .Write (“From Print”);
}
}//test
Public delegate void D name ();
Code in main ()
Test t = new Test ();
D name d = new D name (t. print);
D();
Console. Read Line ();
OBS:-
Delegates encapsulate some information like class name and method names.
Working with Multicast Delegates :-
- MCD holds the addresses of many functions.
- MCD holds the sequence of functions
- MCD supports arithmetic + and _ operations.
- ‘+’ operator add a function in to the sequence.
- ‘_’ operator removes a function from the sequence.
OBS:
D6= D5 – D3 – D2
= GM GA - GM GA - GA
= GM
Example on MCD :-
- open console Application Project
- Code for GD (before Main ())
Class Test
{
Public void M1 ()
{
Console . Write (“GM ”);
}//M1
Public void M2 ()
{
Console . Write Line (“GA”);
}//M2
}// Test
Public delegate void XYZ ();
Static void Main (Strings [] args)
- Code in main ()
{
Test t = new Test ();
XYZ = d1, d2, d3,d4,d5,d6;
D1 = new XYZ (t. M1);
D2 = new XYZ (t.M2);
D3 = d1 + d2;
Console. Write line (“From D3 :”);
D3 ();
D4 = d3 +d3;
Console. Write line (“From D4 :”);
D4 ();
D5 = d4- d1;
Console. Write line (“From D5:”);
D5 ();
D6 =d5-d3-d2;
Console. Write line (“From D6 :”);
D6 ();
Console. Read line ();
}