It's something that someone else wrote or maybe you wrote, but you can encapsulate all of your ideas or your functionality inside this thing called a function.

它是别人或你自己写的，但是你可以压缩你所有的想法,或者你这个东西里面的功能叫做一个函数。

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Now, how can I use code that someone else wrote?

那么，我们怎样才能用别人写的代码呢？

哈佛公开课 - 计算机科学课程节选

stdio h This file here is called standard I/O or stdio.h and this is just another text file someone else wrote many years ago and by using that line of code there, I'm telling the computer, give me acces to this code that this other person wrote that's in that file.

在这里的头文件称为标准输入输出文件或,这是由某位前人编写的文本文件,我们只需要刚才所述的一行代码，就能告诉电脑，让我连接到,这个前人在那个文件中写的代码。

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

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。

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So you have to somehow convert the source code, the C code into 0s and 1s and for that process there exist this tool called a compiler that someone else wrote that takes this stuff as input and produces this stuff as output.

所以你必须把源代码，即C语言代码转换成二进制文件,这个过程就需要我们提到的编译器了,它是由别人编写的一个软件，以这些代码作为输入,将会产生的输出。

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Well, for a thing called main which itself is a function but a function I wrote, a tool I am writing at the moment not like printf which someone else wrote long ago, I have to say where does main start, where does main end, and I do that by using these curly braces.

至于这个名曰main的函数,由我们自己写的函数，也是一个工具,只不过由我们自己编写，而不是像printf那样已经由前人写好了,我们必须要说明main在哪开始，在哪结束，这样我们就要用到大括号了。

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So with the fact that I'm now just back at my prompt is a good thing so now GCC hello c if I type this command GCC hello.c, this is gonna run this program that Apple wrote in this case GCC or someone else wrote called GCC.

也就是说我们现在安全返回,说明一切正常,现在我输入这条命令：,这代表运行hello，c这个程序,是由“Apple“或其他人编写的，名为。

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