在我们编写代码的时候，通常会因为一些不好的习惯犯一些细小的错误，而就是因为这些细小的错误使我们多了很多弯路，这里就详细的说明了怎样避免这些错误,其中有很多防卫性编程的知识-code in our preparation time, it is usually because of some bad habits made some small mistakes, But it is because these small mistakes we make a lot of mistakes, here on the detailed descr iption of how to avoid these mistakes, a lot of defensive programming knowledge