在使用cin ..阅读输入之前刷新cout为什么？ [英] Flushing of cout prior to reading input using cin .. why?

问题描述

为什么cout在cin开始阅读之前必须刷新？他们不是不同的缓冲区吗？我可以读取输入到缓冲区，同时把它放在输出缓冲区（刷新前）.. 2个不同的缓冲区。我在这里感到困惑。

Why does cout has to be flushed before cin starts reading? Aren't they of different buffer? I can have reading of input into a buffer while same time putting it on output buffer (before flushing) .. 2 different buffers. I am confused here.

推荐答案

它不必刷新。默认情况下，流绑定在一起，所以当你做的事情：

It doesn't have to be flushed. By default the streams are tied together so that when you do things like:

cout << "Enter your name:";
cin >> name;

在输入开始之前出现提示 - 这只是一个方便的功能。但是，您可以解除他们：

the prompt appears before the input starts - this is just a convenience feature. However, you can untie them:

cin.tie( static_cast<ostream*>(0) );

之后cout将不会被flush（在输入cin之前）。

following which cout will not (necessarily) be flushed before input is performed on cin.

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