classes and objects_oops programming.pptx

classes and objects_oops programming.pptx

• 1.
  CLASSES AND OBJECTS
• 2.
  Introduction to classes Importantfeature of C++ Bjarne Stroustrup named ‘C with classes’ Features provided Abstraction Encapsulation Inheritance Polymorphism
• 3.
  Need for Class Wayof binding the data and its associated functions together Used to create user defined datatype
• 4.
  Declaration of class Classis defined using keyword class followed by the name of the class
• 5.
  General Form class classname { private: variabledeclaration; function declaration; protected: variable declaration; function declaration; public: variable declaration; function declaration; };
• 6.
  Class Access Specifiers Public Private protected
• 7.
  Definition of classmembers Example class result { private: char name[10]; int rollno,mark1,mark2,mark3,total; public: void accept(); void display(); }; Data members Member functions
• 8.
  Defining methods ofa class Inside the class definition(Inline member function) Outside the class definition(outline/non-inline member function) Without defining function, class definition will become incomplete Defining outside the class uses Scope Resolution Operator(::)
• 9.
  Syntax for definingoutside the class returntype classname::functionname(list) { function definition } Example: void add::display() { function definition }
• 10.
  Creating objects To makeuse of a class, the variables of that class type have to be declared The class variables are called as objects(instance of class) Example: student s; instance of class student
• 11.
  Methods for creatingobjects Global object Declared outside all the functions or placed immediately after the closing brace Local object Declared within a function and it cannot be accessed from outside the function
• 12.
  Methods for creatingobjects - Example class add { ------ ------ }a1; //global object add a2; //global object int main() { add a3; //local object -------- }
• 13.
  Memory allocation ofobjects Memory space is allocated for data members when the objects are created No memory is allocated for member functions since all the objects use the same member functions
• 14.
  Memory allocation ofobjects- Example #include<iostream> using namespace std; class add { int num1,num2,result; public: void read() { cout<<“Enter number1:”; cin>>num1; cout<<“Enter number2:”; cin>>num2; } void sum() { result=num1+num2; } }; void add::display() { cout<<“Result=“<<num1<<“+”<<num2< <“=“<<result<<endl; } int main() { add obj1,obj2; obj1.read(); obj1.sum(); obj1.display(); obj2.read(); obj2.sum(); obj2.display(); getch(); return 0; }