Question

因此，我得到了一个任务，以制作一个程序，该程序允许用户按顺序选择三个喜欢的目的地。重复直到用户决定停止。一旦用户决定中止，程序将根据用户的喜好显示每个目的地收到的总票数。一个用户将具有三个首选项，如果程序重复四次，则意味着将记录四个用户的首选项。因此，在这种情况下，总共记录了12个首选项。

我试图限制循环的输入，但是似乎只能在程序开始时不需要的决定下起作用，我想将其完全删除。

此外，我尝试限制每个决策的输出，但是它将只运行一次，然后继续执行下一个选择。有什么方法可以获取持久输入提示，该输入提示仅在输入有效后才会继续。

最后，有什么办法可以通过使用switch / break语句而不是if / else来改善代码吗？

这是我的代码：

cout << "Do you want to go forth with this program?\nType y to confirm. The 
program will exit if anything else is entered: ";
cin >> Decision;    


    while (Decision=="y") 
    {

        cout << "\n\nNow please enter the code for which your destination corresponds to: " << endl;    //first decision
        cin >> Choice1;   

            if (Choice1 == 1) 
            {
                LasVegas1++;        
            }

            else if (Choice1 == 2) 
            {
                Tokyo1++;
            }

            if (cin.fail())
            {     
            cout << "Please enter a valid choice" << endl;
            continue;
            }

        cout << " \nNow please enter the second code: " << endl;    //second decision
        cin >> Choice2;

            if (Choice2 == 1) 
            {
                LasVegas2++;        
            }

            else if (Choice2 == 2) 
            {
                Tokyo2++;
            }

            else 
            {
                cout << "\nError! Please enter a valid code as shown above!\n";
                cout << "\nNow please enter the second code: ";
                cin >> Choice2;
            }




        cout << " \nNow please enter the third code: " << endl;  //third decsion
        cin >> Choice3;

            if (Choice3 == 1) 
            {
                LasVegas3++;        
            }

            else 
            {
                cout << "\nError! Please enter a valid code as shown above!\n";
                cout << "\nNow please enter the third code: ";
                cin >> Choice3;
            }


        cout << " \nDo you wish to select three more destinations? (Y/N): " << endl;
        cin >> Decision;

    }

Answer 1

我要做的是将所有城市变量放入array，然后将三组代码转换为for loop。像这样：

for(int i = 0; i < 3; i++) {
    if(Choice1 == 0) {
       rome[i]++;
    }
    //etc

这样一来，您无需重复相同的代码3次。另外，您只需要一个Choice变量。（您可以在循环的每次迭代中将其重置）

此外，您可以实现switch语句以稍微清理代码：

switch(Choice1) {  
        case 1:
            LasVegas1++;        
            break;

        case 2:
            Tokyo1++;
            break;

        case 3:
            London1++;
            break;

        case 4:
            Paris1++;
            break;

        case 5:
            Dubai1++;
            break;

        case 6:
            Mumbai1++;
            break;

       case 7:
            NewYork1++;
            break;

        case 8: 
         Sydney1++;
         break;

        case 9:
            Auckland1++;
            break;

        case 10:
            Rome1++;
         break;

        case 11:
            Other1++;
           break;
      }

Answer 2

是的，您可以使用switch语句进行改进。还有一些应该做的事情，叫做do while循环。

Answer 3

使用“ 开关”和“ 断开”可以大大简化此操作。

就像我编写的代码一样。看看：

字符输入；

int选择；

void Permission（）{

cout << "Do you want to go forth with this program ?                     (y to confirm)" << flush;
cin >> input;
cout << endl;

}

void Decision1（）{

if（input =='y'）{

    cout << "Now please enter the code for which your destination corresponds to : " << flush;
    cin >> choice;

    switch (choice) {
    case 1: 
        cout << "LasVegas " << endl;
        break;
    case 2:
        cout << "Tokyo " << endl;
        break;
    case 3:
        cout << "London " << endl;
        break;
    case 4:
        cout << "Paris " << endl;
        break;
    case 5:
        cout << "Dubai " << endl;
        break;
    case 6:
        cout << "Mumbai " << endl;
        break;
    case 7:
        cout << "New York " << endl;
        break;
    case 8:
        cout << "Sydney " << endl;
        break;
    case 9:
        cout << "Auckland " << endl;
        break;
    case 10:
        cout << "Rome " << endl;
        break;
    case 11:
        cout << "Other " << endl;
        break;
    default:
        cout << "Invalid option. Enter Again : " << flush;
        cin >> choice;
    }
    cout << endl;
}

}

void Decision2（）{

cout << "Now please enter the second code: " << flush;
cin >> choice;

switch (choice) {

case 1:
    cout << "LasVegas " << endl;
    break;
case 2:
    cout << "Tokyo " << endl;
    break;
case 3:
    cout << "London " << endl;
    break;
case 4:
    cout << "Paris " << endl;
    break;
case 5:
    cout << "Dubai " << endl;
    break;
case 6:
    cout << "Mumbai " << endl;
    break;
case 7:
    cout << "New York " << endl;
    break;
case 8:
    cout << "Sydney " << endl;
    break;
case 9:
    cout << "Auckland " << endl;
    break;
case 10:
    cout << "Rome " << endl;
    break;
case 11:
    cout << "Other " << endl;
default:
    cout << "Invalid option. Enter Again : " << flush;
    cin >> choice;
}
cout << endl;

}

void Decision3（）{

cout << "Now please enter the third code: " << flush;
cin >> choice;

switch (choice) {
case 1:
    cout << "LasVegas " << endl;
    break;
case 2:
    cout << "Tokyo " << endl;
    break;
case 3:
    cout << "London " << endl;
    break;
case 4:
    cout << "Paris " << endl;
    break;
case 5:
    cout << "Dubai " << endl;
    break;
case 6:
    cout << "Mumbai " << endl;
    break;
case 7:
    cout << "New York " << endl;
case 8:
    cout << "Sydney " << endl;
    break;
case 9:
    cout << "Auckland " << endl;
    break;
case 10:
    cout << "Rome " << endl;
    break;
case 11:
    cout << "Other " << endl;
    break;
default:
    cout << "Invalid option. Enter Again : " << flush;
    cin >> choice;
}
cout << endl;

}

int main（）{

Permission();
Decision1();
Decision2();
Decision3();

system("PAUSE");
return 0;

}

我不知道当用户输入错误的选项时如何在默认情况下获得循环。我曾经给过一次“ cin ”。如果您知道如何更新此问题。

用户输入C ++的功能循环

3 个答案: