哪位高手能理解小弟我从书上抄写的代码？

谁能理解我从书上抄写的代码？？？
#include <iostream>
using   namespace   std;
enum   TYPE{HORSE,PEGASUS};
class   Horse
{
public:
virtual   void   Gallop(){cout < < "Galloping...\n ";}
private:
int   itsage;
};
class   Pegasus:public   Horse
{
public:
virtual   void   fly(){cout < < "I   can   fly!I   can   fly!I   can   fly!\n ";}
};
const   int   NumberHorses   =5;
int   main()
{
Horse   *Ranch[NumberHorses];
Horse*pHorse;
int   choice,i;
for(i=0;i <NumberHorses;i++)
{
cout < < "(1)Horse(2)Pegasus; ";
cin> > choice;
if(choice==2)
pHorse=new   Pegasus;
else
pHorse=new   Horse;
Ranch[i]=pHorse;
}
cout < < "\n ";
for(i=0;i <NumberHorses;i++)
{
Pegasus   *pPeg=dynamic_cast <Pegasus*> (Ranch[i]);
if(pPeg)
pPeg-> fly();
else
cout < < "just   a   horse\n ";
delete   Ranch[i];
}
return   0;
}

Pegasus   *pPeg=dynamic_cast <Pegasus*> (Ranch[i]);究竟是什么意思？？？？


------解决方案--------------------
编译的时候记得打开rtti

class base
{
public :
virtual void Do()
{
cout < < "base::Do " < <endl;
};
};

class test:public base
{
public:
void Do()
{
cout < < "test::Do " < <endl;
};
void Func()
{
cout < < "test::Func " < <endl;
};
};


int main(int argc, char* argv[])
{
base* p = new test;
p-> Do();
test* p1 = dynamic_cast <test*> (p);
if( p1 )
p1-> Func();
test* p2 = static_cast <test*> (p);
if( p2 )
p2-> Func();
return 0;
}