Demonstrate the function call operator. - C++ Class

C++ examples for Class:Operator Overload

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Description

Demonstrate the function call operator.

Demo Code

#include <iostream>
using namespace std;
class Box {//from   w ww . j  a  va  2  s.c o  m
   int x, y, z; // 3-D coordinates
   public:
   Box() { x = y = z = 0; }
   Box(int i, int j, int k) { x = i; y = j; z = k; }
   // Create two function call operator functions.
   Box operator()(Box obj);
   Box operator()(int a, int b, int c);
   // Let the overloaded inserter be a friend.
   friend ostream &operator<<(ostream &strm, Box op);
};
// Overload function call. 
// returns a Box object whose coordinates are the midpoints between the invoking object and obj.
Box Box::operator()(Box obj)
{
   Box temp;
   temp.x = (x + obj.x) / 2;
   temp.y = (y + obj.y) / 2;
   temp.z = (z + obj.z) / 2;
   return temp;
}
// Overload function call. Take three ints as parameters. This version adds the arguments to the coordinates.
Box Box::operator()(int a, int b, int c)
{
   Box temp;
   temp.x = x + a;
   temp.y = y + b;
   temp.z = z + c;
   return temp;
}
// The Box inserter is a non-member operator function.
ostream &operator<<(ostream &strm, Box op) {
   strm << op.x << ", " << op.y << ", " << op.z << endl;
   return strm;
}
int main()
{
   Box objA(1, 2, 3), objB(10, 10, 10), objC;
   cout << "This is objA: " << objA;
   cout << "This is objB: " << objB;
   objC = objA(objB);
   cout << "objA(objB): " << objC;
   objC = objA(10, 20, 30);
   cout << "objA(10, 20, 30): " << objC;
   // Can use the result of one as an argument to another.
   objC = objA(objB(100, 200, 300));
   cout << "objA(objB(100, 200, 300)): " << objC;
   return 0;
}

Result


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