Virtual Function

Virtual Function

   #include <iostream>
   using namespace std;
   class BaseClass
   {
     public:
       int i;
       BaseClass(int x)
       {
         i = x;
       }
       virtual void myFunction()
       {
         cout << "Using BaseClass version of myFunction(): ";
         cout << i << '\n';
       }
   };
   class DerivedClass1 : public BaseClass
   {
     public:
       DerivedClass1(int x) : BaseClass(x) {}
       void myFunction()
       {
         cout << "Using DerivedClass1's version of myFunction(): ";
         cout << i*i << '\n';
       }
   };
   class DerivedClass2 : public BaseClass
   {
   public:
       DerivedClass2(int x) : BaseClass(x) {}
       void myFunction()
       {
         cout << "Using DerivedClass2's version of myFunction(): ";
         cout << i+i << '\n';
       }
   };
   int main()
   {
     BaseClass *p;
     BaseClass ob(10);
     DerivedClass1 derivedObject1(10);
     DerivedClass2 derivedObject2(10);
     p = &ob;
     p->myFunction(); // use BaseClass's myFunction()
     p = &derivedObject1;
     p->myFunction(); // use DerivedClass1's myFunction()
     p = &derivedObject2;
     p->myFunction(); // use DerivedClass2's myFunction()
     return 0;
   }