include stdio h The next line of code says include standard io.h which just as a little sanity check contains among other things, printf.

接着的一行代码写着,这个库文件包含一些我们常用的函数,譬如，printf函数。

哈佛公开课 - 计算机科学课程节选

The standard library, that first line of code, it's not strictly necessary but any time you use a function, a tool that someone else wrote that lives in that so called library, you do need that include line as we'll see.

标准库函数--第一行代码，严格来说，不是每次都要写的，但是一旦你调用某个别人写，的函数，而这个函数又恰巧位于标准库里面,你就要像我们看到的这样，把它include进去。

哈佛公开课 - 计算机科学课程节选

cs50 h It's not called standard io.h, it's called cs50.h. That's where the code we wrote for you will live and then we'll see how to do this in examples today onward but we wrote for you some tools, some functions that calls GetChar for get a character.

当然不是标准输入输出库了，而是叫做,这里面有一些我们写的代码,等一下我会举几个例子,我们写了一些函数,比如GetChar，意思是得到一个变量。

哈佛公开课 - 计算机科学课程节选