-------------------
Delegate
-------------------
Delegate let us store a function to store in a variable. In C , this is similar to the function pointer defined using typedef, which usually uses a function pointer.
The keyword that is delegated to use is delegate. Hey, you will understand what is entrustion:
Example:
Delegate Int Operation (int Val1, int val2);
Public Int Add (int Val1, Int Val2)
{
RETURN VAL1 VAL2;
}
Public int subtract (int Val1, int Val2)
{
Return VAL1- VAL2;
}
Public void perform ()
{
Operation Oper;
Console.writeline ("Enter or -");
String Optor = console.readline ();
Console.WriteLine ("Enter 2 Operands");
String opnd1 = console.readline ();
String Opnd2 = console.readline ();
INT VAL1 = Convert.TOINT32 (OPND1);
INT VAL2 = Convert.TOINT32 (OPND2);
IF (Optor == " "))
Oper = new operation (add);
Else
Oper = New Operation (Subtract);
Console.writeLine ("Result = {0}", Oper (VAL1, VAL2));
}
-------------------
Inheritance and polymorphism
-------------------
C # only allows for inheritance, multi-inheritance is to be implemented by an interface.
Example:
Class Parent {
}
Class Child: Parent
-------------------
Virtual method
-------------------
In addition to achieving the virtual method in subclasses, the virtual method implements the polymorphic concept C # with C . The parent class uses the same Virtual keyword. Use an Override keyword from each class of overloading virtual methods.
Class Shape
{
Public Virtual Void Draw ()
{
Console.writeline ("Shape.DRAW");
}
}
Class Rectangle: Shape
{
Public Override Void Draw ()
{
Console.writeline ("Rectangle.DRAW");
}
}
Class Square: Rectangle
{
Public Override Void Draw ()
{
Console.writeline ("Square.Draw");
}
}
Class mainclass
{
Static void
Main
(String [] ARGS)
{
Shape [] SHP = New Shape [3];
Rectangle Rect = New Rectangle ();
SHP [0] = New Shape ();
SHP [1] = Rect;
SHP [2] = New Square ();
SHP [0] .draw ();
SHP [1] .draw ();
SHP [2] .draw ();
}
}
Output T:
Shape.draw
Rectangle.draw
Square.draw
-------------------
Use "New" to hide the parent method
-------------------
You can define a subclass into a new method version, hide the version in the base class. You can define a new version using the New keyword. Think about the example below, it is the modified version of the above example. Note When I use the New keyword in the Rectangle class instead of the output of the Override keyword.
Class Shape
{
Public Virtual Void Draw ()
{
Console.writeline ("Shape.DRAW");
}
}
Class Rectangle: Shape
{
Public New Void Draw ()
{
Console.writeline ("Rectangle.DRAW");
}
}
Class Square: Rectangle
{
// Didn't be overloaded here
Public New Void Draw ()
{
Console.writeline ("Square.Draw");
}
}
Class mainclass
{
Static void
Main
(String [] ARGS)
{
Console.writeline ("Using Polymorphism:");
Shape [] SHP = New Shape [3];
Rectangle Rect = New Rectangle ();
SHP [0] = New Shape ();
SHP [1] = Rect;
SHP [2] = New Square ();
SHP [0] .draw ();
SHP [1] .draw ();
SHP [2] .draw ();
Console.writeline ("Using WITHOUT POLYMORPHISM:");
Rect.draw ();
Square sqr = new square ();
SQR.DRAW ();
}
}
Output:
USING POLYMORPHISM
Shape.draw
Shape.draw
Shape.draw
USING WITHOUT POLYMORPHISM:
Rectangle.draw
Square.draw
The polymorphism here does not use the DRAW method of the Rectangle class as a manifestation of the Shape's DRAW method. Instead, it will think this is a different way. Therefore, in order to avoid naming conflicts between the parent class and subclass, we use the New modifier.
Note: You cannot use two versions of one of the following methods below, that is, one version with a New modifier, the other is the version of Override or Virtual modifier. As explained above, I cannot add another method named DRAW to the Rectangle class with the Virtual or Override method. Similarly, in the Square class, I cannot overload the virtual DRAW method of the Square class.
-------------------
Call base class member
-------------------
If the subclass and the base class have the same name, to avoid naming conflicts, access the base class data member and the letter to use a keyword base. In the example below, let's take a look at how to call the constructor of the base class and how to use the data member.
Public Child (int Val): Base (VAL)
{
MYVAR = 5;
Base.myvar;
}
or
Public Child (int Val)
{
Base (VAL);
MYVAR = 5;
Base.myvar;
--------------------------------
In the future supplement:
This article is only a quick overview of a C # language so that you can familiarize with this language. Although I have tried to discuss all the major C # concepts in a concise and comprehensive code, I think there is still a lot to fill in the discussion.
In the future, I will join more commands and concepts that have not been discussed, such as events, and more. I also want to write some Dongdong for Windows programming for C # beginners.
Reference:
Our Most Commonly Known MSDN
Inside C # by Tom Archer
A Programmer's Introduction To C # by Eric Gunnerson
Beginning C # by Karli Watson
Programming C # (O'Reilly)
About the Author
AISHA IS A MASTER OF Science In Computer Science from Quaid-I-Azam Univeristy. She Has Worked in VC 6, MFC, ATL, COM / DCOM, ActiveX, C , SQL, AND SO FORTH. THESE DAYS SHE IS WORKING ON .NET Framework and c #. INSPIRED WITH Nature, She Loves to Seek Knowledge. Sheeeps a free source code and articles web site at http://aishai.netfirms.com.
History
Date posted:
June 13, 2003
