如何在显示游戏菜单时处理无效输入

Question

#include <iostream>
#include <string>
using namespace std;
int main() { //Program starts
    cout << "-------------------------------" << endl;
    cout << "Welcome to Ninjas vs. Samurais!" << endl; //The intro
    cout << "-------------------------------" << endl;
    string newAdventure;
    string chosenKind;
    cout << "Hello, new solder! Are you ready for your adventure to begin,       yes or no?n"; //Asks you if you are ready
    cin >> newAdventure;//Takes in if you are ready or not
    if (newAdventure == "yes" || newAdventure == "Yes" || newAdventure ==    "Yes!") { //Asks if they are ready
        cout << "Great!n" << endl;
    }
    else if (newAdventure == "no" || newAdventure == "No" || newAdventure ==     "No!") { //Asks if they are ready
        cout << "Too bad!n" << endl;
    }
    else {
        cout << "Please type a yes or no answer!n";
    }  
    system("PAUSE");
    return 0;
}

如果用户没有输入有效的答案，我该如何让他们重新开始提问？我必须使用循环吗？如果是这样，我将如何做？

Answer 1

是的，你必须使用循环。像这样：

while(cin >> newAdventure)//Takes in if you are ready or not
  {
    if (newAdventure == "yes" || newAdventure == "Yes" || newAdventure ==    "Yes!") { //Asks if they are ready
        cout << "Great!n" << endl;
        break;
    }
    else if (newAdventure == "no" || newAdventure == "No" || newAdventure ==     "No!") { //Asks if they are ready
        cout << "Too bad!n" << endl;
        break;
    }
    else {
        cout << "Please type a yes or no answer!n";
    }  
  }

一旦您的答案有效，break关键字将退出循环，否则，它将继续运行。

Answer 2

您可以添加如下条件：

while(true)    
{
cout << "Hello, new solder! Are you ready for your adventure to begin,       yes or no?n"; //Asks you if you are ready
cin >> newAdventure;//Takes in if you are ready or not
if (newAdventure == "yes" || newAdventure == "Yes" || newAdventure ==    "Yes!") { //Asks if they are ready
    cout << "Great!n" << endl;
    break;
}
else if (newAdventure == "no" || newAdventure == "No" || newAdventure ==     "No!") { //Asks if they are ready
    cout << "Too bad!n" << endl;
    break;
}
else {
    cout << "Please type a yes or no answer!n";
}  
}