数学逻辑功能不正确

我正在从事此练习，这是完整的，但是在计算老年人折扣时，数学在某个地方必须是错误的。我使用的软件运行了这两个输入以检查问题。

• 2010n212（运行良好）

• 2010y212（没有给我预期的结果）

这使我相信问题在于双重确定限制函数的老年人折扣部分。

预期的结果是"会员资格成本= $ 162.80" ，但我的代码给我"会员资格成本= $ 152.00"

我不确定这里怎么了。我希望第二组眼睛能帮助找到它。预先感谢您。

这是代码：

// headers
#include <iostream>
#include <iomanip>
#include <string>
using namespace std;
// prototypes
void displayGeneralInformation ();
void readNecessaryInformation (double& regularCostPerMonth,
                               double& costPerPersonalTrainingSession,
                               bool& seniorCitizen, int& numberOfSessions,
                               int& numberOfMonths);
double determineMembershipCost (double regularCostPerMonth,
                                double costPerPersonalTrainingSession,
                                bool seniorCitizen, int numberOfSessions,
                                int numberOfMonths);
// main
int main()
{
    //variables
    double regularCostPerMonth;
    double costPerPersonalTrainingSession;
    bool seniorCitizen;
    int numberOfSessions;
    int numberOfMonths;
    double cost;
    // print menu
    // calls
    // call displayGeneralInformation
    displayGeneralInformation ();
    // call readNecessaryInformation
    readNecessaryInformation (regularCostPerMonth,
                              costPerPersonalTrainingSession,
                              seniorCitizen, numberOfSessions,
                              numberOfMonths);
    // call determineMembershipCost
    cost = determineMembershipCost (regularCostPerMonth, costPerPersonalTrainingSession, seniorCitizen, numberOfSessions,                                                       numberOfMonths);
    // Display cost of membership
    cout << "nThe membership cost = $" << setprecision(2)<< fixed << cost << endl; 
    return 0;
}
// displayGeneralInformation function definition
void displayGeneralInformation ()
{
    cout << "nWelcome to Stay Healthy and Fit center." << endl;
    cout << "This program determines the cost of a new membership." << endl;
    cout << "If you are a senior citizen, then the discount is 30% off of the regular membership price." << endl;
    cout << "If you buy membership for twelve months and pay today, the discount is 15%." << endl;
    cout << "If you buy and pay for 6 or more personal training session today, the discount on each session is 20%." << endl;
}
// readNecessaryInformation function definition
void readNecessaryInformation (double& regularCostPerMonth,
                              double& costPerPersonalTrainingSession,
                              bool& seniorCitizen, int& numberOfSessions,
                              int& numberOfMonths)
{
    cout << "nEnter the cost of a regular membership per month: $";
    cin >> regularCostPerMonth;
    cout << "Enter the cost of one personal training session: $";
    cin >> costPerPersonalTrainingSession;
    cout << "Are you a senior citizen (Y,y/N,n): ";
    char ch;
    cin >> ch;
    if (ch == 'Y' || ch == 'y')
        seniorCitizen = true;
    else
        seniorCitizen = false;
    cout << "Enter the number of personal training sessions bought: ";
    cin >> numberOfSessions;
    cout << "Enter the number of months you are paying for: ";
    cin >> numberOfMonths;
}
// determineMembershipCost function definition
double determineMembershipCost (double regularCostPerMonth, double costPerPersonalTrainingSession, bool seniorCitizen, int numberOfSessions, int numberOfMonths)
{
    double cost = regularCostPerMonth * numberOfMonths;
    if (seniorCitizen)
    {
        cost = cost - (regularCostPerMonth * 0.30 * numberOfMonths);
    }
    if (numberOfMonths >= 12)
    {
        cost = cost - (regularCostPerMonth * 0.15 * numberOfMonths);
    }
    cost = cost + (costPerPersonalTrainingSession * numberOfSessions);
    if (numberOfSessions > 5)
    {
        cost = cost - (costPerPersonalTrainingSession * 0.20 * numberOfSessions);
    }
    return cost;
}