Class with scope resolution in c++

Scope resolution operator in c++:

How to give function definition at out of the class in c++?

How to use scope resolution operator in c++ using class?

• The scope resolution operator is used to access data members and member function at the out of the classes.
• It mainly used to return value at the class.
• This operator symbol is::( double colon).

Syntax:

1. class class_name

   {

   Access_specifier:

   return type function_declaration(parameter_list);

   };

    

   //function definition

   return_type class_name :: fuction_name(parameter_list)

   {

             //function body

   }

    

   void main()

   {

             function_calling(parameter_list);

   }

Example program:

1. #include<iostream.h>

   #include<conio.h>

   #include<iomanip.h>

   class std

   {

   public:

   //function declaration

   int total(int,int,int,int,int);

   float average(int);

   void display(int ,char [], int ,int ,int ,int ,int ,int ,float );

   };

    

   int std :: total(int m1,int m2, int m3,int m4,int m5)

   {

   int tot;

   tot = m1+m2+m3+m4+m5;

   return tot;

   }

    

   float std :: average(int tot)

   {

   float avg;

   avg =tot/5;

   return avg;

   }

    

   void std ::  display(int sno,char *name, int m1,int m2,int m3,int m4,int m5,int tot,float avg)

   {

   cout<<"\n Student details............";

   cout<<"\n Student id is : "<<sno;

   cout<<"\n Student name is : "<<name;

   cout<<"\n Five subject marks : "<<m1<<setw(5)<<m2<<setw(5)<<m3<<setw(5)<<m4<<setw(5)<<m5;

   cout<<"\n Total mark for five subject :"<<tot;

   cout<<"\n Average mark for five subject :"<<avg;

   }

    

   void main()

   {

   int sno,m1,m2,m3,m4,m5,tot;

   float avg;

   char name[30];

   clrscr();

   cout<<"\n Enter student number : ";

   cin>>sno;

   cout<<"\n Enter student name : ";

   cin>>name;

   cout<<"\n Enter Five subject mark : ";

   cin>>m1>>m2>>m3>>m4>>m5;

   std s;//object declaration

   tot=s.total(m1,m2,m3,m4,m5);

   avg=s.average(tot);

   s.display(sno,name,m1,m2,m3,m4,m5,tot,avg);

   getch();

   }

Output:

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Method overloading and overriding in Python

 Overriding:

• Method overriding is a mechanism in which a subclass inherits the methods of the superclass and sometimes the subclass modifies the implementation of a method defined in the superclass.
• That means if subclass (Derived class) has the same method as declared in the parent class (base class).
• Method overriding is used for runtime polymorphism.

Rules for Java Method Overriding:

• The method must have the same name as in the parent class
• The method must have the same parameter as in the parent class.
• There must be inherited.
• A static method cannot be overridden. It can be proved by runtime polymorphism.

Syntax:

1. class base_class_name:

   def method_name(parameter_list):

             //Statement

    

   class derived_class_name(base_class_name):

   base_class_method(parameter_list):

             //Statement

Example program:

1. #method overriding or runtime polymorphism

   class Shape:

       result=0

       def area(self):

           print("\n\tCalculating area of Rectangle,Circle,Triangle .........")

   class Rectangle(Shape):

       def area(self):

           l=int(input("Enter length: "))

           w=int(input("Enter width: "))

           result=l*w; #area=length*width;

           print("Area of rectangle : ",result)

          

   class Circle(Shape):

       def area(self):

           r=float(input("Enter radius  of circle : "))

           result=3.14*r*r; #area=3.14*radius*radius;

           print("Area of circle : ",result)

    

   s=Shape()

   s.area()

   r=Rectangle()

   r.area()

   c=Circle()

   c.area()

Output:

Method overloading:

• Overloading is a mechanism in which we can use many methods having the same function name but can pass the different numbers of parameters or different types of parameters.
• In python, doest not call the data types at function definition.
• So python does not support method overloading.

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Polymorphism in python

 Polymorphism:

• Poly means many and prism means form so polymorphism means many forms.
• It is used to perform a single action in different ways.
• For example,
• Action is drawn and it performance maybe draw a line or draw a circle.

Compile-time polymorphism:

• The runtime polymorphism is also called static polymorphism.
• It is the best example is method overriding.

Example program:

1. #method overriding or runtime polymorphism

   class Shape:

       result=0

       def area(self):

           print("\n\tCalculating area of Rectangle,Circle,Triangle .........")

   class Rectangle(Shape):

       def area(self):

           l=int(input("Enter length: "))

           w=int(input("Enter width: "))

           result=l*w; #area=length*width;

           print("Area of rectangle : ",result)

          

   class Circle(Shape):

       def area(self):

           r=float(input("Enter radius  of circle : "))

           result=3.14*r*r; #area=3.14*radius*radius;

           print("Area of circle : ",result)

    

   s=Shape()

   s.area()

   r=Rectangle()

   r.area()

   c=Circle()

   c.area()

Output:

Note:

• If you need to detail learning of method overloading and method overriding concepts then please click the below link to helpful.
• https://www.whereisstuff.com/2021/03/method-overloading-and-overriding-in.html

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Encapsulation in C++

Encapsulation:

• Data encapsulation is used to hide the implementation details from users.
• If a data member is private it means it can only be accessed within the same class. 
• No outside class can access private data member (variable) of other class.

Syntax:

1. class class_name

   {

   private data_members;

   public: methods()

   {

   }

   };

Example program:

1. #include<iostream.h>

   #include<conio.h>

   class Account {

       private:

        int account_number;

        int account_balance;

       public:

        void show_Data() {

             account_number=13456;

             account_balance=5000;

             cout<<"\nBefore deposit of account XXXXX"<<account_number<<" number of balance :"<<account_balance;

       }

        void deposit(int a) {

             if (a < 0) {

                 cout<<"\nGiven amount is wrong...";

             }

             else{

                    account_balance = account_balance + a;

                    cout<<"\n\nAfter deposit of current balance :"<<account_balance;

             }

       }

   };

   void main()

       {

             clrscr();

             Account ac;

             ac.show_Data();

             ac.deposit(200);

             getch();

       }

Output:

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Method overloading and overriding in C++

 Overriding:

• Method overriding is a mechanism in which a subclass inherits the methods of the superclass and sometimes the subclass modifies the implementation of a method defined in the super class.
• That means if subclass (Derived class) has the same method as declared in the parent class (base class).
• Method overriding is used for runtime polymorphism.

Rules for Java Method Overriding:

• The method must have the same name as in the parent class
• The method must have the same parameter as in the parent class.
• There must be inherited.
• A static method cannot be overridden. It can be proved by runtime polymorphism.

Syntax:

1. class base_class_name

   {

   return_type method_name(parameter_list)

   {

             //Statement

   }

   }

    

   class derived_class_name

   {

   base_class_method(parameter_list)

   {

             //Statement

   }

   }

Example program:

1. #include<iostream.h>

   #include<conio.h>

   class Shape {

   public:

   double a;

       void area() {

   cout<<"\n\tCalculating area of Rectangle,Circle,Triangle .........";

       }

   };

   
   

   class Rectangle:public Shape {

      public:

       void area(float l,float w) {

   cout<<"\n\nEnter length and width of rectangle : ";

   cin>>l>>w;

   a=l*w; //area=length*width;

   cout<<"\nArea of rectangle : "<<a;

       }

   };

   
   

   class Circle:public Shape {

   public:

       void area(float r) {

   cout<<"\n\nEnter radius  of circle : ";

   cin>>r;

   a=3.14*r*r; //area=3.14*radius*radius;

   cout<<"\nArea of circle : "<<a;

       }

   };

   
   

   void main()

   {

   clrscr();

   Shape s;

   s.area();

   Rectangle r;

   r.area(6,3);

   Circle c;

   c.area(3.2);

   getch();

   }

Output:

Method overloading:

• Overloading is a mechanism in which we can use many methods having the same function name but can pass the different numbers of parameters or different types of parameters.

Syntax:

1. class base_class_name

   {

   return_type method_name(parameter_list)

   {

             //Statement

   }

   return_type same_method_name(parameter_list)

   {

             //Statement

   }

   }

Example program:

1. #include<iostream.h>

   #include<conio.h>

   class Shape {

   public:

   double a;

       void area() {

             cout<<"\n\tCalculating area of Rectangle,Circle,Triangle .........";

       }

   };

    

   class Rectangle: public Shape {

      public:

       void area() {

             float l,w;

             cout<<"\n\nEnter length and width of rectangle : ";

             cin>>l>>w;

             a=l*w; //area=length*width;

             cout<<"\nArea of rectangle : "<<a;

       }

   };

    

   class Circle:public Shape {

   public:

       void area() {

             float r;

             cout<<"\n\nEnter radius  of circle : ";

             cin>>r;

             a=3.14*r*r; //area=3.14*radius*radius;

             cout<<"\nArea of circle : "<<a;

       }

   };

    

   void main()

   {

             clrscr();

             Shape s;

             s.area();

             Rectangle r;

             r.area();

             Circle c;

             c.area();

             getch();

   }

Output:

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