问题：
I'm learning C++ and I'm just getting into virtual functions. 我正在学习C ++，并且刚开始使用虚函数。
From what I've read (in the book and online), virtual functions are functions in the base class that you can override in derived classes. 从我阅读的内容（在书中和在线上）中，虚函数是基类中的函数，您可以在派生类中重写这些函数。
But earlier in the book, when learning about basic inheritance, I was able to override base functions in derived classes without using virtual . 但是在本书的前面，当学习基本继承时，我无需使用virtual就可以在派生类中覆盖基本函数。
So what am I missing here? 那我在这里想念什么？ I know there is more to virtual functions, and it seems to be important so I want to be clear on what it is exactly. 我知道虚函数还有很多，这似乎很重要，所以我想弄清楚到底是什么。 I just can't find a straight answer online. 我只是无法在网上找到直接的答案。
解决方案：
参考一： https://stackoom.com/question/A2BT/为什么我们需要C-中的虚函数参考二： https://oldbug.net/q/A2BT/Why-do-we-need-virtual-functions-in-C
来源：oschina
链接：https://my.oschina.net/u/4437974/blog/4308718