我的cin在while循环中被忽略了

Question

我正在尝试将一个简单的问题和数字检查器编码到我的第一个C++程序中.问题是,当我输入一个像两个或三个字符串的字符串时,程序变为无限循环,它忽略了cin函数,将生命重新分配给一个数字.

cout << "How many lives would you like 1 (hard), 2 (medium), or 3 (easy)?" << endl;
cin >> lives;


while(lives != 1 && lives != 2 && lives != 3 && !isdigit(lives))
{
    cout << "You need to input a number, not words." << endl;
    cout << "How many lives would you like 1 (hard), 2 (medium), or 3 (easy)?" << endl;
    cin >> lives;
}

以下是我当前的代码以及您的建议:

    cout << "How many lives would you like 1 (hard), 2 (medium), or 3 (easy)?" << endl;
std::cin.ignore();
std::cin.clear();
if (std::cin >> lives)
{


    while(lives != 1 && lives != 2 && lives != 3)
    {
        cout << "You need to input a number, not words." << endl;
        cout << "How many lives would you like 1 (hard), 2 (medium), or 3 (easy)?" << endl;
        cin >> lives;
    }

}

Answer 1

#include <iostream>
#include <limits>

int main()
{
    int lives = 0;
    std::cout << "How many lives would you like 1 (hard), 2 (medium), or 3 (easy)?" << std::endl;


    while(!(std::cin >> lives) || lives < 1 || lives > 3)
    {
        std::cout << "You need to input a number, not words." << std::endl;
        std::cout << "How many lives would you like 1 (hard), 2 (medium), or 3 (easy)?" << std::endl;
        std::cin.clear();
        std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
    }

    return 0;
}

好的.std::cin.clear();负责重置失败位.std::cin.ignore删除流中剩余的任何错误输入.而且我已经调整了停止条件.(这isDigit是一个冗余的检查,如果生命在1到3之间,那么显然它是一个数字).