Working with OOP synopsis concepts :-
Based on the style of programming the languages are divided in to three types
Procedure structure OOPL
1960’s A! GOL 1970’s
- No loops COBOL
- No arrays BASIC
- NO dynamic ‘C’
- Memory allocation
Problems in C –language :-
P1
Main ()
{
Int Sal = 4000;
Print f (“%d”, Sal);
}
Output:-
~- 700
Problems :-
- Data types limits are not controlled at run time.
P2)
Main ()
{
Int I = 500 * 500/500;
Print f (“%d”, i);
}
Output :-
– 27
Problem 2 :-
No proper implicit procedure for calculation
P3
Long Sal = 5000; // global variable
Main () {}
Void F1() {}
Void F2 () {}
Void Marketing Details ()
{
Long Sale = 500000;
Sale = Sale + Sale ;
}
No Security for the ‘DATA’
- To overcome all the these problems , ANSI (American National Standard Institute) defined a set of rules called as “OOPS”
When a language supports , the following oops concepts then that language is called as object oriented programming language (OOPL).
OOPS concepts :-
- Encapsulation (Data Hiding)
- Abstraction (Providing information)]
- Polymorphism (overloading)
- Inheritance
- Encapsulation is a concept of data hiding.
- Abstraction is a concept of providing full information a bout an entity (data binding)
- Polymorphism is a concept of writing more than one function with same and different arguments.
- Inheritance is a concept of deriving the features from base to derived class
OBS:
- To work with OOPS concepts, classes and object are required.
- Classes is a logical representation
- Object is a physical representation
As per .net , A classes is a collection of
- Fields: private data of classes is called a field.
- Properties: it defines the look and feel of an object
- Methods: when an object can do do is called a method
- Events: what user can do with an object is called an “event”
- Instance of a classes is called as an object
Instance means copy
Syntax to write a class:
Class C1 Name
{
Private int x,y;
Private String s;
Public void print ();
{
Return type
}
Private and public are assess specifiers which provides scope of risibility
Syntax to create an object:-
Logical Diagram on class and object:-
Test obj = new Test()
- Object can access only public data.
- Object can not access private data
EX 1 : on Classes and objects :-
Note :-
Classes must be declared in GD only.
- Open windows forms Application project
- Place a button
- Code in GD (Before button 1 click)
Classes Test
{
Private int x, y ; // fields (or) Reference types
Public void Read (int a, int b) //a and b are value types, local variables.
{
x =a;
y =b;
}
Public void print ()
{
Int K = x +y ;
Message Box >show (“The sum is ” + K);
}//test
Code for Button 1 click
{
Test t1 = new Test ()
T1.Read (10,20);
T1.Print (10,20);
T1.Print (); // output is ‘30’
Test t2 = new Test ();
T2.print (); // output is ‘0’
Test t3 = new Test ();
T3.print (); //error
Test t3 = t1;
T3.print ();//output is ‘30’
}
Execute the project
OBS :-
- Fields of a class are also called Instance variables.
- In C#.net by default every class will be inherited from System. object class
- System. object class contains four methods
- Get Hash code ()
- Get Type ()
- Equals ()
- To string ()
- In C# .net every class contain minimum 4 methods.
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