Now because among its contents is the prototype for print F, that is why, very simply, I can call print F without having to declare its prototype myself.

现在因为在它的内容中是printf的原型，这就是为什么我可以不声明printf函数的原型,而可以调用它。

哈佛公开课 - 计算机科学课程节选

to do sqrt, or square root-- no, I'm going to square root use sqrt, that's the name I'm using here-- square root a hundred different places in some piece of code. Without function, I'd have to copy that piece of code everywhere.

让我做一下准备,想象一下我要调用sqrt或者-,不，我会调用sqrt函数,这是我在这里用的名字，我得把这段代码到处复制。

麻省理工公开课 - 计算机科学及编程导论课程节选