运行下面的程序，观察其输出，体会 i++与++i 的差别。

#include <iostream.h>
int main()
{ 
int myAge = 39; // initialize two integers 
int yourAge = 39; 
cout << "I am: " << myAge<< " years old.\n"; 
cout << "You are: " << yourAge<< " years old\n"; 
myAge++; // postfix increment 
++yourAge; // prefix increment 
cout << "One year passes...\n"; 
cout << "I am: " << myAge<< " years old.\n"; 
cout << "You are: " << yourAge<< " years old\n"; 
cout << "Another year passes\n"; 
cout << "I am: " << myAge++<< " years old.\n"; 
cout << "You are: " <<++yourAge << " years old\n"; 
cout << "Let's print it again.\n"; 
cout << "I am: " << myAge<< " years old.\n"; 
cout << "You are: " << yourAge<< " years old\n"; 
return 0; 
}