I want the function, which is a little tool, a line of code I can include in my own programs and generally those tools live in sections two or three of the manual.

我想要一个函数，那是一个小工具，在我程序中可以包含的一行代码,通常这些工具在手册的第二节,或第三节。

哈佛公开课 - 计算机科学课程节选

All you have to include in your own programs is the so-called header file.

你们自己写的程序只需要包括,头文件就可以了。

哈佛公开课 - 计算机科学课程节选