c-无效的int输入陷入无限循环

这个问题已经在这里有了答案：            >            Infinite loop with cin when typing string while a number is expected                                    4个

do
{
    cout << "Enter the numerator and denominator of the first fraction: ";
    cin >> a >> b;
    cout << endl;
    cout << "Enter the numerator and denominator of the second fraction: ";
    cin >> c >> d;
    cout << endl;
} while (!validNum(a, b, c, d));

...

bool validNum(int num1, int num2, int num3, int num4)
{
    if (cin.fail() || num2 == 0 || num4 == 0)
    {
        if (num2 == 0 || num4 == 0)
        {
            cout << "Invalid Denominator. Cannot divide by 0" << endl;
            cout << "try again: " << endl;
            return false;
        }
        else
        {
            cout << "Did not enter a proper number" << endl;
            cout << "try again: " << endl;
            return false;
        }
    }
    else
        return true;
}

我要尝试做的是确保分母不为零,并且仅输入数字.除零代码可以正常工作,但是当您输入一个char值时,它将进入一个无限循环,并且不知道为什么.有任何想法吗？

解决方法:

if (cin.fail() ... )

输入无效值(即char)后,流中的故障位将打开,validNum将始终返回false,从而导致无限循环.

您需要清除错误状态,并在每次调用后忽略其余输入：

if (std::cin.fail())
{
    std::cin.clear();
    std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
}

标签：c,infinite-loop
来源： https://codeday.me/bug/20191009/1878521.html