为什么里面的cin不会一直停下来获取用户输入? [英] Why cin inside while doesn't stop to get user input?
问题描述
我现在开始使用C ++,所以我想这将是一个非常容易使用的新手问题。
I'm starting now with C++, so I imagine this is gonna be a very easy-newbie question.
那么,为什么 cin >> x行内是否不停止循环来获取用户输入(如果用户输入了字符而不是数字)?
Well, why the "cin >> x" line inside while doesn't stop the loop to get the user input (if the user inputs a character, in place of a number)?
#include <iostream>
using std::cin;
using std::cout;
using std::endl;
int main()
{
int x = 0;
cout << "Please, enter x: ";
cin >> x;
while (!cin)
{
cout << "Please, it must be a number!\n";
cin >> x;
}
cout << "Thanks!.";
cin.ignore();
cin.ignore();
}
我几乎没有学习C ++的两天时间,所以我完全不了解真正的 cin是什么。我尝试使用 cin.sync()和 cin.clear(),但还是没有运气。
而且我知道不可能执行 cin = true或 cout<< cin之类的事情。
I'm barely two days studiying C++, so I'm completely blind about what "cin" really is. I tried with "cin.sync()" and "cin.clear()", but still no luck. And I know it is impossible to do something like "cin=true", or "cout << cin".
推荐答案
嗯,您的程序应该稍作修改
Well, your program should be corrected slightly
#include <iostream>
using std::cin;
using std::cout;
using std::endl;
int main()
{
int x = 0;
cout << "Please, enter x: ";
cin >> x;
while (!cin)
{
cin.clear();
cin.ignore(10000, '\n');
cout << "Please, it must be a number!" << endl;
cin >> x;
}
cout << "Thanks!.";
}
这种方式可以正常工作。关于它的更多信息此处。通常,您需要清除cin中所有错误的内容。
This way it works as expected. More info about it here. In general, you need to clear all the errorneous stuff from cin.
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