哪里'的getchar（）`存储用户输入？ [英] Where does `getchar()` store the user input?

问题描述

我已经开始阅读 C编程语言（K＆安培; R）我有一个关于的getchar（）功能毋庸置疑。

I've started reading "The C Programming Language" (K&R) and I have a doubt about the getchar() function.

例如这个code：

#include <stdio.h>

main()
{
  int c;

  c = getchar();
  putchar(c);
  printf("\n");   
}

键入 toomanychars + <大骨节病> CTRL + <大骨节病> D （EOF）打印刚 T 。我认为这意料之中的，因为它推出的第一个字符。

Typing toomanychars + CTRL+D (EOF) prints just t. I think that's expected since it's the first character introduced.

但随后的另一块code的：

But then this other piece of code:

#include <stdio.h>

main()
{
  int c;

  while((c = getchar()) != EOF) 
    putchar(c);
}

键入 toomanychars + <大骨节病> CTRL + <大骨节病> D （EOF）打印 toomanychars 。

Typing toomanychars + CTRL+D (EOF) prints toomanychars.

我的问题是，为什么出现这种情况，如果我只有一个字符变量？在哪里其余字符存储？

My question is, why does this happens if I only have a single char variable? where are the rest of the characters stored?

编辑：

感谢大家的答案，我开始变得现在...只有一个陷阱：

Thanks to everyone for the answers, I start to get it now... only one catch:

定时的第一程序退出 CTRL + D 而第二打印的整个字符串，然后等待更多的用户输入。为什么它会等待另一个字符串，并且不退出像第一？

The first program exits when given CTRL+D while the second prints the whole string and then waits for more user input. Why does it waits for another string and does not exit like the first?

推荐答案

它就像对待一个文件的输入流。这是因为如果你打开​​了一个文件，其中包含文本toomanychars，并读取或输出它一次一个字符。

It's treating the input stream like a file. It is as if you opened a file containing the text "toomanychars" and read or outputted it one character at a time.

在第一个例子，在没有while循环的，这就像你打开一个文件并读取第一个字符，然后输出它。但是第二个例子将继续读取字符，直到它得到文件结束信号（ CTRL + D 你的情况）就像如果它是从磁盘上的文件读取。

In the first example, in the absence of a while loop, it's like you opened a file and read the first character, and then outputted it. However the second example will continue to read characters until it gets an end of file signal (ctrl+D in your case) just like if it were reading from a file on disk.

在回答你的问题的更新，你使用的是什么操作系统？我跑了它在我的Windows XP的笔记本电脑，它工作得很好。如果我打输入，它会打印出什么，我到目前为止，创建一个新行，然后继续。 （在的getchar（）函数不返回，直到你preSS进入，这是时，有没有在输入缓冲区，当它被称为）。当我preSS CTRL + Z （EOF在Windows中），程序将终止。请注意，在Windows中，EOF必须在自己的行数在命令提示符下一个EOF。我不知道这种行为是在Linux的模仿，或者您可能正在运行的任何系统。

In reply to your updated question, what operating system are you using? I ran it on my Windows XP laptop and it worked fine. If I hit enter, it would print out what I had so far, make a new line, and then continue. (The getchar() function doesn't return until you press enter, which is when there is nothing in the input buffer when it's called). When I press CTRL+Z (EOF in Windows), the program terminates. Note that in Windows, the EOF must be on a line of its own to count as an EOF in the command prompt. I don't know if this behavior is mimicked in Linux, or whatever system you may be running.

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