""you shouldn't use a default argument as a flag upon which to conditionallly execute code. you should instead break the function into two or more overloaded functions""
"在C中,我们常常发现能使程序通过编译,然后我们必须再花力气使它工作。"
"与刚才忽略不满足判定函数的元素不同..."
"But, and this is an important point, as soon as you decide to write your own copy-constructor and assignment operator, the compiler assumes that you know what you’re doing and does not automatically call the base-class versions, as it does in the synthesized functions. If you want the base class ver"