C++ LANGUAGE FUNCTION CALL() OPERATOR OVERLOADING

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C++ LANGUAGE FUNCTION CALL() OPERATOR OVERLOADING

Function Call () Operator Overloading 


The function call operator () can be overloaded for 
objects of class type. When you overload ( ), you are 
not creating a new way to call a function. Rather, you 
are creating an operator function that can be passed an 
arbitrary number of parameters. 

Following example explains how a function call operator () can be overloaded.
 
#include <iostream> 
using namespace std; 
  
class Distance 
{ 
   private: 
      int feet;             // 0 to infinite 
      int inches;           // 0 to 12 
   public: 
      // required constructors 
      Distance(){ 
         feet = 0; 
         inches = 0; 
      } 
      Distance(int f, int i){ 
         feet = f; 
         inches = i; 
      } 
      // overload function call 
      Distance operator()(int a, int b, int c) 
      { 
         Distance D; 
         // just put random calculation 
         D.feet = a + c + 10; 
         D.inches = b + c + 100 ; 
         return D; 
      } 
      // method to display distance 
      void displayDistance() 
      { 
         cout << "F: " << feet <<  " I:" <<  inches << endl; 
      } 
       
}; 
int main() 
{ 
   Distance D1(11, 10), D2; 
 
   cout << "First Distance : ";  
   D1.displayDistance(); 
 
   D2 = D1(10, 10, 10); // invoke operator() 
   cout << "Second Distance :";  
   D2.displayDistance(); 
 
   return 0; 
} 
 
When the above code is compiled and executed, it produces the following result: 

First Distance : F: 11 I:10 
Second Distance :F: 30 I:120