Access base class's virtual if derived class does not redefine it : virtual function « Class « C++ Tutorial

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C++ Tutorial » Class » virtual function 
9.28.2.Access base class's virtual if derived class does not redefine it
#include <iostream> 
using namespace std; 
 
class BaseClass 
public
  virtual void who() { 
    cout << "Base\n"
  
}
 
class DerivedClass1 : public BaseClass 
public
  void who() { 
    cout << "First derivation\n"
  
}
 
class DerivedClass2 : public BaseClass 
// who() not defined 
}
 
int main() 

  BaseClass base_obj; 
  BaseClass *p; 
  DerivedClass1 DerivedClass1_obj; 
  DerivedClass2 DerivedClass2_obj; 
 
  p = &base_obj; 
  p->who();  // access BaseClass's who() 
 
  p = &DerivedClass1_obj; 
  p->who()// access DerivedClass1's who() 
 
  p = &DerivedClass2_obj; 
  p->who()/* access BaseClass's who() because 
               DerivedClass2 does not redefine it */ 
 
  return 0
}
Base
First derivation
Base
9.28.virtual function
9.28.1.A virtual function
9.28.2.Access base class's virtual if derived class does not redefine it
9.28.3.Use virtual functions and polymorphism
9.28.4.A pure virtual function
9.28.5.Multiple virtual member functions called in turn
9.28.6.Class with only virtual methods
9.28.7.Use virtual function to calculate area for different shapes
9.28.8.Use Virtual Functions to change the method behaviour
9.28.9.Why Virtual Functions: one interface, multiple methods
9.28.10.Implementing pure virtual functions
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