Day24

1. 9.5节提到判断方法(predicate function)的概念，简单来说就是许多容器类别: 如link list, queue, stack都有一个方法isEnpty()或是isFull()就是所谓的判断方法。

2. 蚂蚁书有个小优点就是美的段落的有个tips，这里提到从安全性考量传值呼叫的方式传递物件非常好，因为被呼叫的函式没法修改原来的物件，但是大型物件的副本记忆体用量大效率差，所以用指标或参照的方式效率比较好，而传const指标/参照可以结合两者的优点。做法是用指向const资料的指标当参数传入函式

• Pointer to const object
  You can modify the pointer but you can't modify the object:

const Object* object_ptr = object1;
object_ptr = object2;                // Modify pointer, OK
object_ptr->x = 40;                  // Modify object, ERROR

• Const pointer to object
  You can't modify the pointer but you can modify the object:

const Object* object_ptr = object1;
object_ptr = object2;                // Modify pointer, OK
object_ptr->x = 40;                  // Modify object, ERROR

ref :Constant pointers vs. pointer to constants in C and C++