C++ this Pointer

Every object in C++ has access to its own address through an important pointer called this pointer. The this pointer is an implicit parameter to all member functions. Therefore, inside a member function, this may be used to refer to the invoking object.
Friend functions do not have a this pointer, because friends are not members of a class. Only member functions have a this pointer.
Let us try the following example to understand the concept of this pointer:


#include <iostream>
using namespace std;

class Box
      // Constructor definition
      Box(double l=2.0, double b=2.0, double h=2.0)
         cout <<"Constructor called." << endl;
         length = l;
         breadth = b;
         height = h;
      double Volume()
         return length * breadth * height;
      int compare(Box box)
         return this->Volume() > box.Volume();
      double length;     // Length of a box
      double breadth;    // Breadth of a box
      double height;     // Height of a box

int main(void)
   Box Box1(3.3, 1.2, 1.5);    // Declare box1
   Box Box2(8.5, 6.0, 2.0);    // Declare box2

      cout << "Box2 is smaller than Box1" <<endl;
      cout << "Box2 is equal to or larger than Box1" <<endl;
   return 0;


Constructor called.
Constructor called.
Box2 is equal to or larger than Box1