Question

我正在使用C ++为项目创建菜单。在项目的特定部分，我使用switch语句来允许用户在该菜单的不同选项之间进行选择。问题是，当前允许他们多次选择相同的选项。由于每个选项都有一个特定的值，因此它会在该选项的值上加上用户选择该选项的次数。我想将用户可以选择任何选项的次数限制为一次。

编辑：不允许在该项目中使用数组。

void additionalOptionsMenu();

const double VIEW = 50.00;
const double JACUZZI = 40.00;
const double BREAKFAST = 15.00;
const double BED = 12.00;
const double WIFI = 9.00;

int main()
{

    double additionalOptions = 0.00;
    int subChoice;


    do{

           additionalOptionsMenu();

    cin >> subChoice;

        switch (subChoice){

            case 1:
                additionalOptions += VIEW;
                break;
            case 2:
                additionalOptions += JACUZZI;
                break;
            case 3:
                additionalOptions += BREAKFAST;
                break;
            case 4:
                additionalOptions += BED;
                break;
            case 5:
                additionalOptions += WIFI;
                break;
            case 6:
                break;
            default:
                cout << "ERROR";
                break;


        }
        }while (subChoice != 6);

        cout << additionalOptions; 
//Displays the final value of additionalOptions

    return 0;
}


void additionalOptionsMenu()
{
    cout << "\n1. View: $50.00\n"
         << "\n2. Jacuzzi: $40.00\n"
         << "\n3. Breakfast: $15.00\n"
         << "\n4. Extra Bed: $12.00\n"
         << "\n5. Internet Access: $9.00\n"
         << "\n6. Previous Menu\n";
}

Answer 1

您不会在基本交换机的情况下找到该功能。使用变量将该功能添加到switch语句中，以检查是否已使用了选项是可行的。为此，可在代码的+ =行周围添加一条if语句。

但是，从长远来看，使用开关外壳以外的结构可能会使您的生活更轻松。

Answer 2

最简单的方法是使用一系列布尔值来跟踪用户已选择的内容：

void additionalOptionsMenu();

const double VIEW = 50.0;
const double JACUZZI = 40.0;
const double BREAKFAST = 15.0;
const double BED = 12.0;
const double WIFI = 9.0;

enum AmenitysOption {
    , AMENITY_NONE
    , AMENITY_VIEW
    , AMENITY_JACUZZI
    , AMENITY_BREAKFAST
    , AMENITY_BED
    , AMENITY_WIFI
    , AMENITY_MAX
};

bool amenityOptions[AMENITY_MAX] = {};

int main()
{

    double additionalOptions = 0.0;
    int subChoice;
    do {
        additionalOptionsMenu();
        cin >> subChoice;
        if(amenityOptions[subChoice]) {
            cout << "\nYou've already picked that option.\n";
            continue;
        }
        switch (subChoice) {
            case AMENITY_NONE:
                break;
            case AMENITY_VIEW:
                additionalOptions += VIEW;
                amenityOptions[AMENITY_VIEW] = true;
                break;
            case AMENITY_JACUZZI:
                additionalOptions += JACUZZI;
                amenityOptions[AMENITY_JACUZZI] = true;
                break;
            case AMENITY_BREAKFAST:
                additionalOptions += BREAKFAST;
                amenityOptions[AMENITY_BREAKFAST] = true;
                break;
            case AMENITY_BED:
                additionalOptions += BED;
                amenityOptions[AMENITY_BED] = true;
                break;
            case AMENITY_WIFI:
                additionalOptions += WIFI;
                amenityOptions[AMENITY_WIFI] = true;
                break;
            case AMENITY_MAX:
                break;
            default:
                cout << "\nERROR";
                break;
        }
    } while (subChoice < AMENITY_MAX);

    cout << additionalOptions; 
    //Displays the final value of additionalOptions
    return 0;
}


void additionalOptionsMenu()
{
    cout << "\n1. View: $50.00\n"
         << "\n2. Jacuzzi: $40.00\n"
         << "\n3. Breakfast: $15.00\n"
         << "\n4. Extra Bed: $12.00\n"
         << "\n5. Internet Access: $9.00\n"
         << "\n6. Previous Menu\n";
}

如何防止在switch语句中多次选择相同的选项/值

2 个答案: