null pointer call in c++

#include <iostream>

class Foo 
{
    public:    
         static void bar() 
        {
            std::cout << "NULL->bar()" << std::endl;
        }
};    

int main(void) 
{
    Foo * foo = NULL;
    foo->bar(); //<=> Foo::bar();
    return 0; 
} 

空指針可以引用類的static函數，等價于classname::static_fun();。