I can certainly try to write the number 13 there, but bam, my program very likely will crash if this chunk of memory was not given to me previously by the operating system and maybe it is owned by the operating system.

我当然可以在那里写下数字13，但是“嘣“,如果这块内存不是系统预先给我的,我的程序很可能会崩溃,可能这块内存,是系统本身使用的。

哈佛公开课 - 计算机科学课程节选

Only the operating system has controlling of byte zero NULL in the computer's RAM and so if a function ever returns null, aka zero, well, something must have gone wrong because that can't possibly belong to me that memory because by human convention zero is owned by the operating system; not by a program I wrote.

只用操作系统在内存中能够控制,字节0，并且如果一个函数返回，或者说0，好的，可能出错了,因为那可能是不属于我的内存,因为惯例上，0是由操作系统拥有的,而不是由我的程序拥有的。

哈佛公开课 - 计算机科学课程节选

So that is a flag that tells the compiler that I want to use or link into my own program code that someone else wrote that lives somewhere else on the system whose moniker is CS50.

所以那是一个标记，用来告诉编译器我想使用,或连接我自己的程序代码到一个叫做CS50的系统中的程序,可能其他人在那个系统写了这些程序。

哈佛公开课 - 计算机科学课程节选