Using Virtual Functions to control the behaviour : virtual function « Class « C++

1. C++
2. Class
3. virtual function

Using Virtual Functions to control the behaviour

   
#include <iostream>
using namespace std;
   
class convert {
protected:
  double val1;  // initial value
  double val2;  // converted value
public:
  convert(double i) {
    val1 = i;
  }
  double getconv() { return val2; }
  double getinit() { return val1; }
   
  virtual void compute() = 0;
};
   
// Liters to gallons.
class l_to_g : public convert {
public:
  l_to_g(double i) : convert(i) { }
  void compute() {
    val2 = val1 / 3.7854;
  }
};
   
// Fahrenheit to Celsius
class f_to_c : public convert {
public:
  f_to_c(double i) : convert(i) { }
  void compute() {
    val2 = (val1-32) / 1.8;
  }
};
   
int main()
{
  convert *p;  // pointer to base class
   
  l_to_g lgob(4);
  f_to_c fcob(70);
   
  // use virtual function mechanism to convert
  p = &lgob;
  cout << p->getinit() << " liters is ";
  p->compute();
  cout << p->getconv() << " gallons\n";  // l_to_g
   
  p = &fcob;
  cout << p->getinit() << " in Fahrenheit is ";
  p->compute();
  cout << p->getconv() << " Celsius\n";  // f_to_c
   
  return 0;
}
  
    
    
  

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