执行cin后计算标准输入中的字符数 [英] Counting the number of characters in standard input after a cin has been executed

问题描述

我有一些基本看起来像这样的代码

I have some code that basically looks like this

int a;
cin>>a;

if(!cin.good())
{
    std::cin.clear();
    std::cin.ignore(2);

    // set some default value for 'a' and display some messages
}

如果我给出一个整数（如预期的那样），或者如果我尝试弄乱它并给出最多2个字符，这将很好地工作。例如。 'ss'，但是如果我给3个字符输入'sss'，则最后一个's'不会被忽略，并被接受作为我程序中的其他cin的输入。

this works fine if I give an integer (as expected) or if I try to mess with it a little and give upto 2 chars. eg. 'ss' , but if I give a 3 char input 'sss' , the last 's' is not ignored and is accepted as the input for some more cin's that I have in my program down the line.

第一个cin发生后，有什么方法可以计数标准输入（缓冲区吗？）中的字符数，所以我可以放心地忽略所有这些字符。

Is there any way to count the number of characters in the standard input (buffers?) after the first cin has happened, so I can safely ignore all of them.

推荐答案

这是如何工作的？它应该忽略输入缓冲区中所有可用的内容，以防止以后消耗第三个 s 。它使用 std :: basic_streambuf :: in_avail 。

How does this work? It should ignore everything available in the input buffer, preventing that third s from being consumed later. It uses std::basic_streambuf::in_avail.

std::cin.ignore(std::cin.rdbuf()->in_avail());

如果该方法无效，则可以尝试忽略，直到到达换行符为止。

If that fails to work, you can try to ignore until you reach a line feed.

std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');

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