Object Oriented Programming (oops) Concepts

oops concept

 

What is the purpose of Data Hiding?

 

 • Data hiding is mistaken as data security. 

 •By hiding data a programmer can avoid mishandling of data by the code outside the class. 

 • Data is accessible only within a class.

 • Only the functions of a class, knows what processing should be done on that data 

  Encapsulation vs Abstraction 

 •A Class is used for Encapsulation as well as Abstraction 

 •Encapsulation means combining related data members and functions together. 

 • Encapsulation is achieved using a class. 

 • Abstraction means hiding data and showing required functions. 

 •Abstraction is achieved using encapsulation and data hiding. Private and public. 

  structure vs class •

C++ supports both structure and class  

 • structure in C++ can have data members and member functions. 

 •All members of a structure are public by default. 

 • class can contain data members and member functions 

 •All members of a class are private by default.

  What is “this” pointer? •

 It represents current object. 

 • It is useful in avoiding variable name conflict. 

 Example for current object. 

class Test{ 

private: 

 int value; 

public: 

void fun(int x){

 this->value=x;

 } 

}; 

int main(){

 Test t1,t1; // both t1 and t2 are having “value” 

t1.fun(10); // “this” inside fun means “value” of t1. 

t2.fun(20); // “this” inside fun means “value” of t2. 

} 

Example for variable name conflict.

 class Test{ 

 private:

 int value; 

public: 

void fun(int value){

 // here parameter name and data member name is same “value” to access data member “this” is used. this->value=value; 

 }

}