C++ examples for Class:Virtual Function
Creating a virtual function by placing the keyword virtual before the function's return type in the declaration
#include <iostream> #include <cmath> using namespace std; class One/*from w w w. j a v a 2s .co m*/ { protected: double a; public: One(double = 2.0); // constructor virtual double f1(double); // member function double f2(double); // another member function }; // implementation section for the base class One::One(double val) // constructor { a = val; } double One::f1(double num) // member function { return (num/2); } double One::f2(double num) // another member function { return (pow(f1(num),2)); // square the result of f1() } // declaration section for the derived class class Two : public One { public: virtual double f1(double); // overrides class One's f1() }; // implementation section for the derived class double Two::f1(double num) { return (num/3); } int main() { One object_1; // object_1 is an object of the base class Two object_2; // object_2 is an object of the derived class // call f2() using a base class object call cout << "The computed value using a base class object call is " << object_1.f2(12) << endl; // call f2() using a derived class object call cout << "The computed value using a derived class object call is " << object_2.f2(12) << endl; return 0; }