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Constructor

Constructor is a special class member function that class has the same name as that of its class.It is used to initialize the value to data member of a objects.When the object is created.
Syntax:
Class Class_name
{
private:
data members;
--------------;
protected:
data members;
public:
data members;
public:
class_name(parameters list) //declare and define a constructor
 {
  -------;
  -------;
}};
Properties of a Constructor
  1.  Constructor name must be same as that of in class name.
  2. Constructor does not return any value even not void.
  3. Constructor is executed automically when object of a class is created.
  4. Constructor is used to initialize value to the data member of a object ate the time of in creation.
  5. Constructor must have public access specifier.
  6. Constructor cannot be static.
  7. Constructor cannot access its address.
  8. If no constructor is define that compiler will automically execute a default constructor.
  9. A program has multiple constructor having zero or more parameter that compiler are not execute default constructor.
Example:-  class rectangle
                 {
                  private:
                     int length;
                     int breath;
                  public:
                      rectangle()  // constructor
                      {
                       length=10;
                       breath=20;
                      }
                       void area()
                      {
                        int area=length*breath;
                        cout<<"Area="<<area;
                       }};
                    void main()
                   {
                    rectangle a1;
                    a1.area();
                    getch();
                    }
Output of this program:-
  Area=200

Types of constructor

Default constructor 

Default  constructor is a constructor that does contain any argument it is also called constructor with no parameter.
Syntax:-  Class class_name
               {
                access specifier:
                 Data members;
                 --------------;
                public:
                class_name()   //default constructor
                 {
                 ------------;
                 ------------ ;
                }}:
Example:-  class rectangle
                 {
                  private:
                     int length;
                     int breath;
                  public:
                      rectangle()  // constructor
                      {
                       length=10;
                       breath=20;
                      }
                       void area()
                      {
                        int area=length*breath;
                        cout<<"Area="<<area;
                       }};
                    void main()
                   {
                    rectangle a1;
                    a1.area();
                    getch();
                    }
Output of this program:-
  Area=200

Parameterized constructor

Parameterized constructor is a constructor that have one or more argument.The parameterized constructor is used to gave different value to data member of different object.
Syntax:-  Class class_name
               {
                Data members;
                ---------------;
                class_name(arguments) //passing one or more arguments
                 {
                  -------------;
                  -------------;
                  }};








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