C 使用存储在 char 中的变量

Question

int main()
{
    float S = 7.5, R = 5.85, D = 5.95, liters, price;
    char answer;
    printf("Choose one of the following fuels or X to quit:\nS - gas 98 \nR - gas 95\nD - diesel fuel\n");
    scanf("%c", &answer);
    switch (answer)
    {
        case 'S': case 's':
            printf("You selected to fuel with gas 98\n");
            break;
        case 'R': case 'r':
            printf("You selected to fuel with gas 95\n");
            break;
        case 'D': case 'd':
            printf("You selected to fuel with disel fuel\n");
            break;
        case 'X': case 'x':
            printf("Thank you.\n");
            break;
}
    printf("The price list is:\ngas98 - 7.5 NIS\ngas98 - 5.85 NIS\ndiesel - 5.95 NIS\n");
    printf("How much liters would you like to fuel?\n");
    scanf("%f", &liters);
    price = answer * liters;
    printf("You choose to fuel %0.0f\nThe price is:%0.0f\n", liters, price);
    return 0;
}

大家好，正如您所看到的，我正在尝试让程序告诉客户他购买的价格(价格 = 答案 * 升)。作为回答，他输入了一个存储的字母(R、S、D)。它不是应该使用我将其声明为浮点变量的值吗？因为当我回答 * 升时，我得到了错误的值，即:客户选择 100 升，而 S，答案应该是 750 (100 * 7.5)，但事实并非如此。

我对 C 或任何其他编程语言都很陌生。感谢您的帮助。

Answer 1

你不能这样做... answer 包含一个值，不能简单地用它的名称来表示另一个变量。您可以做的就是像这样在交换机中分配基本价格，并进一步使用它来计算最终价格:

int main()
{
    float liters, price, basePrice;
    char answer;
    printf("Choose one of the following fuels or X to quit:\nS - gas 98 \nR - gas 95\nD - diesel fuel\n");
    scanf("%c", &answer);
    switch (answer)
    {
        case 'S': case 's':
            printf("You selected to fuel with gas 98\n");
            basePrice = 7.5;
            break;
        case 'R': case 'r':
            printf("You selected to fuel with gas 95\n");
            basePrice = 5.85;
            break;
        case 'D': case 'd':
            printf("You selected to fuel with disel fuel\n");
            basePrice = 5.95;
            break;
        case 'X': case 'x':
            printf("Thank you.\n");
            return 0;
    }
    printf("The price list is:\ngas98 - 7.5 NIS\ngas98 - 5.85 NIS\ndiesel - 5.95 NIS\n");
    printf("How much liters would you like to fuel?\n");
    scanf("%f", &liters);
    price = basePrice * liters;
    printf("You choose to fuel %0.0f\nThe price is:%0.0f\n", liters, price);
    return 0;
}