Different Ways of Implementing Factories

#include <iostream>

class SimpleBaseClass
   {
   public:
      virtual int  getValue()          = 0;
      virtual void setValue(int value) = 0;
   };

class SimpleClass1 : public SimpleBaseClass
   {
   public:
      int  getValue()          {return m_value;}
      void setValue(int value) {m_value = value;}
   private:
      int m_value;
   };

class SimpleClass2 : public SimpleBaseClass
   {
   public:
      int  getValue()          {return m_value*100;}
      void setValue(int value) {m_value = value;}
   private:
      int m_value;
   };

class SimpleClassFactory
   {
   public:
      SimpleBaseClass *createInstance1() {return new SimpleClass1;}
      SimpleBaseClass *createInstance2() {return new SimpleClass2;}
   };

void main()
{
SimpleBaseClass    *simpleInstance     = NULL;
SimpleClassFactory  simpleClassFactory;

simpleInstance = simpleClassFactory.createInstance1();
simpleInstance->setValue (123);
std::cout << simpleInstance->getValue() << std::endl;
delete simpleInstance;

simpleInstance = simpleClassFactory.createInstance2();
simpleInstance->setValue (123);
std::cout << simpleInstance->getValue() << std::endl;
delete simpleInstance;
}