mem_fun与mem_fun_ref的区别

一句话：container<ClassType*>就用mem_fun，container<ClassType>就用mem_fun_ref

参考：

http://www.cplusplus.com/reference/functional/mem_fun/

http://www.cplusplus.com/reference/functional/mem_fun_ref/

其实这里的本质可以看这篇随笔：

http://www.cnblogs.com/qrlozte/p/4453786.html

假设我们把这篇随笔的dosomething_five改为：void dosomething_five(MemberFuncType ptr, MyClass* obj)

实现如下：

void dosomething_five(MemberFuncType ptr, MyClass *obj)
{
    (obj->*ptr)(5);
}

假设改为：void dosomething_five(MemberFuncType ptr, MyClass &obj)

实现如下：

void dosomething_five(MemberFuncType ptr, MyClass &obj)
{
     MyClass *p_obj = &obj;  
    (p_obj->*ptr)(5);
}

这其实就是mem_fun和mem_fun_ref的区别