Classes

1. Classes Sujana Jyothi C++ Workshop Day 2

2. A class in C++ is an encapsulation of data members and functions that manipulate the data. • A class is a mechanism for creating user-defined data types. • Once you create a class type, you can declare one or more objects of that class type • Example: class X { /* define class members here */ }; int main() { X xobject1; // create an object of class type X X xobject2; // create another object of class type X }

3. Function members in classes: Functions declared inside a class can be any of the following types: Ordinary member functions Constructors Destructors class Example_class //Sample Class for the C++ Tutorial    {       private:         int x; //Data member          int y; // Data member        public:          Example_Class() //Constructor for the C++ tutorial          {              x = 0;             y = 0;         }       ~Example_Class() //destructor for the C++ Tutorial        { }       int Add()  //ordinary member function      {          return x+y;      }};

4. Access level: • The classes in C++ have 3 important access levels. Private, Public and Protected. Private:    The members are accessible only by the member functions or friend functions. Protected:    These members are accessible by the member functions of the class and the classes which are derived from this class. Public: Accessible by any external member.

5. // classes example #include <iostream> using namespace std; class CRectangle { int x, y; public: void set_values (int,int); int area () {return (x*y);} }; void CRectangle::set_values (int a, int b) { x = a; y = b; } int main () { CRectangle rect; rect.set_values (3,4); cout << "area: " << rect.area(); return 0; }