C++ OOPS: PART 3 Overview

POLYMORPHISM

It means single things existing in multiple forms.

Real life example: A boy can be someone's brother or son or father or husband.

\*Function Overloading*

Function name same, argument lists are different.

CODE:

class A
   public:
     void sum (int a, int b){
        cout << a+b;
     }
     void sum (int a, int b, intc){
       cout << a+b+c;
     }
};

int main ()
A obj;
obj. sum (10,20);
obj.sum (10,20,30);
return 0;
}

\*OPERATOR Overloading*

SYNTAX:

return_type operator<op>(argument list)

CODE:

class complex{
    private:
      int real, imag;
    public:
      complex (int r= 0, int i=0){
             real = r;
             imag=i;
}
complex operator + (Complex const & obj)
{
complex res;
res.real = real + obj.real;
res.imag = imag + obj.imag;
return res;
}
void print(){
     cout << real <<< "+i" << imag <<endl;
}
};
int main{
complex c1 (10,5), c2 (2,4);
complex c3=c1+c2;
c3.print();
return 0;
}

\*VIRTUAL FUNCTION*

It is a member function that is declared within a base class and is redefined by a derived class.

When we refer to a derived class object using a pointer or reference to the base class, we can virtual function for that object and execute the derived class.

CODE:

class A{
    public:
      virtual void display(){
           cout << "base endl;
      }
      void show(){
          cout<<"base"<<endl;
      }
};
class B : public A
    public:
       void display(){
          cout << "basel" << endl;
}
       void show(){
          cout << "base2"<<endl;
}
};

int main(){
A*bptr;
B d;
bptr=&d;

bptr->display();
bptr->show();
return 0;
}

ABSTRACTION

It means implementation hiding. It increases the reusability, avoid duplication.

Real life example: With a laptop we can do many things like play games, movies, etc. It does not show the inside process of how its doing the things.

CODE:

#include <iostream>    
using namespace std;    
 class Sum    
{    
private: int x, y, z; // private variables  
public:    
void add()    
{    
cout<<"Enter two numbers: ";    
cin>>x>>y;    
z= x+y;    
cout<<"Sum of two number is: "<<z<<endl;    
}    
};    
int main()    
{    
Sum sm;    
sm.add();    
return 0;    
}

ENCAPSULATION

It means wrapping up of data member and function(data hiding).

Real life example: Take a capsule, it has two parts one is solid part and second is powder particles i.e one is data member which having some properties ,states and other part is function having methods , behaviour.

WHY?

->Data hiding-security increases

->code reusability

->unit testing

CODE:

#include <iostream>
#include <string>

using namespace std;

class Person {
private:
    string name;
    int age;
public:
    Person(string name, int age) {
    this->name = name;
    this->age = age;
    }
    void setName(string name) {
    this->name = name;
    }
    string getName() {
    return name;
    }
    void setAge(int age) {
    this->age = age;
    }
    int getAge() {
    return age;
    }
};

int main() {
Person person("John Doe", 30);

cout << "Name: " << person.getName() << endl;
cout << "Age: " << person.getAge() << endl;

person.setName("Jane Doe");
person.setAge(32);

cout << "Name: " << person.getName() << endl;
cout << "Age: " << person.getAge() << endl;

return 0;
}