C++ LANGUAGE THIS POINTER

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C++ LANGUAGE THIS POINTER

this Pointer  


Every object in C++ has access to its own address through 
an important pointer called thispointer. 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 
{ 
   public: 
      // 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(); 
      } 
   private: 
      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 
 
   if(Box1.compare(Box2)) 
   { 
      cout << "Box2 is smaller than Box1" <<endl; 
   } 
   else 
   { 
      cout << "Box2 is equal to or larger than Box1" <<endl; 
   } 
   return 0; 
} 
When the above code is compiled and executed, it produces the following result: 
Constructor called. 
Constructor called. 
Box2 is equal to or larger than Box1