c++ - 验证用户输入为整数 : User has to enter input twice

Question

我提示用户输入一个整数值。当值不正确时，程序运行。但是，当用户输入整数时，用户需要输入两次。

我查看了有关如何使用 while 循环捕获错误输入的其他教程，那部分对我有用。但是，需要输入两次整数值才能运行程序。

#include <iostream>
using namespace std;

int main() {
    cout << "*************************************************" << endl;
    cout << "******************|DVD Library|******************" << endl;
    cout << "*************************************************" << endl;
    cout << "1.\tAdd DVD" << endl;
    cout << "2.\tDelete DVD" << endl;
    cout << "3.\tSearch DVD" << endl;
    cout << "4.\tList All DVDs in the Library" << endl;
    cout << "5.\tAdd DVD to Favorites List" << endl;
    cout << "6.\tDelete DVD from Favorites List" << endl;
    cout << "7.\tSearch DVD in Favorites List" << endl;
    cout << "8.\tList All DVDs in Favorites List" << endl;
    cout << "9.\tQuit" << endl;
    cout << "*************************************************" << endl;

    int input;
    cin >> input;
    while (!(cin >> input)) {
        cin.clear();
        while (cin.get() != '\n')
            continue;
        cout << "Please enter an integer --> " << flush;
    }
    if (input < 1 || input > 9) {
        cout << "Invalid input! Please try again!" << endl;
    }
    return 0;
}

Answer 1

你要求输入两次:

cin >> input;
while(!(cin >> input )){

删除第一行可能会如您所愿。