常量指针与指针常量，非常容易混淆，在网络和各种教程上看了各式各样的对比的记忆技巧，当时可以区分，但过段时间，又搞不清楚了。看到C++作者的一句描述后，“啪”一下，就记住了，也许这辈子都不会忘记了，除非得了老年痴呆~~呵呵，与大家分享一下：
When using a pointer, two objects are involved: the pointer itself and the object pointed to. “Prefixing” a declaration of a pointer with const makes the object, but not the pointer, a constant. To declare a pointer itself, rather than the object pointed to, to be a constant, we use the declarator operator *const instead of plain *.定义指针常量时，我们使用 *const 代替 *。
