4. 初始化和清除

As the computer revolution progresses, "unsafe" programming has become one of the major culprits that makes programming expensive.

初始化和清除是程序设计安全性的两个最重要的问题。

C++为我们引入了构造函数的概念，Java也沿用了这个概念，但新增了自己的垃圾收集器。