如何从std :: cin读取直到流结束？ [英] How to read from std::cin until the end of the stream?

问题描述

我的问题是，我想从 std :: cin 中读取输入，但是不知道输入多长时间。另外我还必须 $ ，并且不能使用：string 。
我有两种处理方法：
a）用户输入文本，当他按下[ENTER]时，程序停止读取。
b）用户将 std :: cin 重定向到文件（例如 .\a.oput<文件）可以容纳多行。

My problem is, that I want to read the input from std::cin but don't know how long the input is. Also I have to char and can't use std::string. There are two ways I have to handle: a) The user inputs text and when he hits [ENTER] the program stops reading. b) The user redirects std::cin to a file (like .\a.oput < file) which can hold multiple lines.

编辑：刚刚注意到，std :: cin.eof（）始终为false

Just noticed that std::cin.eof() is always false also in the case of reading form a file.

对于a）我可以读取直到\n出现。对于b）编辑：否（我可以读到std :: cin.eof（）出现。）
但是当我不知道我要的是a）还是ab ）问题，我该如何中断阅读过程？

For a) I could read until \n occures. For b) No (I could read until std::cin.eof() occures.) But when I don't know whether I'm getting an a) or a b) problem, how can I break the reading process?

这就是我的a）...

This is what I have for a) ...

char buffer = ' ';
while(std::cin >> std::noskipws >> buffer && buffer != '\n')
{
    // do some stuff with buffer
}

...和b）

char buffer = ' ';
while(std::cin >> std::noskipws >> buffer)
{
    // do some stuff with buffer
}

我也知道有 std :: cin.tellg（）

编辑：因此，似乎在文件输入流终止的情况下， std :: cin>>的方式std :: noskipws>>缓冲区获取 false 。
上面的代码对a）的作用：

So it seems like in case of the file the input streams gets terminated, in the way that std::cin >> std::noskipws >> buffer gets false. What the code above does for a):

• 它等待用户输入并按[ENTER]


• 然后循环遍历用户在最后一行输入的每个字符。


• 然后再次等待用户进行输入，然后按[ ENTER]


• 无限等待处理循环

• It waits for the user to make an input and press [ENTER]
• Then it loops through every char entered by the user on the last line.
• Then it waits again for the user to make an input and press [ENTER]
• Infinite-waiting-processing-loop

那我该怎么办？

推荐答案

您可以要求输入始终以EOF结尾（意思是要求 ^ D的命令行被按下），然后照常使用b的过程。然后，这也会启用来自cmdline的多行输入

You could require the input to always end EOF (meaning from commmand line requiring ^D to be pressed) and then use the process for b as always. This would then enable multiline input from cmdline as well

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