Question

这是提示我还没有得到所有这些但是：

实施一个名为GasPump的类，用于在加油站对泵进行建模。 GasPump对象应该能够执行以下任务： - 显示分配的气体量 - 显示分配的气体总量 - 设定每加仑汽油的成本 - 显示每加仑汽油的成本 - 在每次新使用之前重置分配的气体量和充电量 - 跟踪分配的气体量和总电量

在实施GasPump等级时，您应该假设气泵已经分配每秒.10加仑的汽油。在main（）中编写一个提示用户的测试程序输入每加仑汽油的成本和他们想要抽出汽油的秒数。然后，显示泵送的加仑气体的数量，每加仑气体的成本，和天然气的总成本。

我在计算支付金额时遇到问题，并且一直遇到逻辑错误。由于这个代码代表它会编译，但它会为计算收费金额提供垃圾。

#include <iostream>
#include <iomanip>

using namespace std;

class GasPump{
    public:
            void setCostPerGallon(double cpg){
                    costPerGallon = cpg;
            }

            double getCostPerGallon(){
                    return costPerGallon;
            }
            void setAmountDispensed(int seconds){
                    const double dispense = 0.10;
                    sec = seconds;
                    amountDispensed = dispense * sec;
            }

            int getAmountDispensed(){
                    return amountDispensed;
            }
//here is the function I am having problems with, at least I think.
            void setAmountCharged(double costPerGallon, double     amountDispensed){
                    amountCharged = costPerGallon * amountDispensed;
            }

            double getAmountCharged(){
                    return amountCharged;
            }

    private:
            double costPerGallon;
            int sec;
            double amountCharged, amountDispensed;
};

int main() {
    double cpg = 0.0;
    int seconds = 0;
    GasPump pump;

    cout << "Enter the cost per gallon of gas:";
    cin  >> cpg;
    while(cpg <= 0.0) {
        cout << "Enter a value greater than 0:";
        cin  >> cpg;
    }
    pump.setCostPerGallon(cpg);

    cout << "Enter the amount of seconds you want to pump gas for:";
    cin  >> seconds;
    while(seconds <= 0.0) {
        cout << "Enter a value greater than 0:";
        cin  >> seconds;
    }
    pump.setAmountDispensed(seconds);

    cout << "The gas pump dispensed " << pump.getAmountDispensed() << " gallons of gas." << endl
         << "At $" << pump.getCostPerGallon() << " per gallon, your total is $"
         << fixed << setprecision(2) << pump.getAmountCharged() << "." << endl;

    return 0;

Answer 1

您永远不会调用pump.setAmountCharged(...)，因此成员变量amountCharged是编译器在您实例化pump时通常将其初始化的任何内容（通常为0）;

要解决此问题，请先删除成员变量amountCharged，然后在调用getAmountCharged时计算金额，或在调用setAmountCharged之前适当调用getAmountCharged

这是第一个解决方案：

class GasPump {
    ...
    double getAmountCharged() {
        return costPerGallon * amountDispensed;
    }
    ...
};

C ++在类中传递变量并获得逻辑错误

1 个答案: