我试图写一个代码使用类的向量

我要做的是使用类的向量，而不是并行向量，将所有数据存储在代码的"收据"部分。

我首先做的是使用并行向量来做到这一点(这就是在代码中编写的内容)，但现在我需要使用类的向量，我不确定如何做到这一点。正确的做法是什么?

#include <iostream>
#include <string>
#include <cmath>
#include <cctype>
#include <iomanip>
#include <vector>
#include <fstream>
#include <cstdlib> 
using namespace std;

vector <string> flavor;
vector <string> sizes;
vector <double> price;


void printWelcomeMessage() {
    cout << "Welcome to My Frozen Yogurt!" << endl;
    cout << endl;
    cout<< endl;
}

char toLowerCase (char c) {
    char c_lower = c;
    if ( (c >= 'A') && (c <= 'Z')) c_lower = c + 32;
    return c_lower;
}

void toLowerCase (string& str) {
    for (int k=0; k< str.size(); k++) {
       str[k] = toLowerCase (str[k]);
    }
    return;
}


double getYogurtSize(string& yogurtSize) {
    double subtotal=0.;
    const double TAX= 0.0875, SMALLSIZE= 2.19, MEDIUMSIZE = 3.49, LARGESIZE = 4.49;

    cout << "What size would you like? Please enter small, medium, or large: ";
    getline(cin,yogurtSize);
    toLowerCase(yogurtSize);
    //push_back to enter content into vector
    sizes.push_back(yogurtSize);
    //pop_back to delete any times the user mispells the size
    if (yogurtSize != "small" && yogurtSize != "medium" && yogurtSize != "large")
        sizes.pop_back();

    while (yogurtSize != "small" && yogurtSize != "medium" && yogurtSize != "large") {
            cout << "What size would you like? Please enter small, medium, or large: ";
            getline (cin, yogurtSize);
            sizes.push_back(yogurtSize);
        }

    if (yogurtSize== "small") {
        subtotal += SMALLSIZE;
        price.push_back(SMALLSIZE); }
    else if (yogurtSize == "medium") {
        subtotal += MEDIUMSIZE;
        price.push_back(MEDIUMSIZE); }
    else if (yogurtSize=="large") {
        subtotal+= LARGESIZE;
        price.push_back(LARGESIZE); }
    return subtotal;
}
void getYogurtFlavors(string& flavor1, string& flavor2, string& flavor3) {
    cout << "Enter flavor 1: ";
    getline (cin, flavor1);
    toLowerCase (flavor1);
    //use push_back to into content into vector
    flavor.push_back(flavor1);
    flavor.push_back("-");

    cout << "Enter flavor 2: ";
    getline (cin, flavor2);
    toLowerCase(flavor2);
    flavor.push_back(flavor2);
    flavor.push_back("-");

    cout << "Enter flavor 3: ";
    getline (cin, flavor3);
    toLowerCase(flavor3);
    flavor.push_back(flavor3);
    flavor.push_back("-");
}

// function printOrder prints out the flavors of each input
void printOrder (string yogurtSize, string flavor1, string flavor2, string flavor3, int){
    int orderNumber= 0;
    orderNumber++;
    cout<< endl;
    cout << "************************" << endl;
    cout  << "Order: " << orderNumber << flavor1.substr(0,4) << "-" << flavor2.substr(0,4) << "-"<< flavor3.substr(0,4) << " " << yogurtSize  << endl;
    cout << "************************" << endl;
    cout << endl;

    return; 
}

bool addAnotherOrderQ(){
    string order;
    string yes = "yes";
    string no = "no";
    bool moreorders= true;
    cout << "Would you like another order? ";
    getline (cin, order );
    while (order != yes && order != no) {
        cout << "Would you like another order? Please enter yes or no: ";
        getline (cin, order);
        cout << endl;
    }
    if (order == no){
        moreorders= false;
        cout << endl;
    }
    return moreorders;
}

void printTotalCosts (double& subtotal, int& orderNumber) {
    const double TAX= 0.0875;
    int setpre= 2;
    int totalwidth=15;
    int taxwidth= 9;
    int subwidth =12;
    int itemwidth= 6;
    cout << "===================== Receipt ===========================" << endl;
    cout << endl;
    // for for loops to print the size, flavors, and price in the receipt screen, and in the file
    for (int i=0; i< flavor.size(); i++) {
        cout  <<  flavor[i].substr(0,4)<< " ";
    }
    for (int i=0; i< sizes.size(); i++) {
        cout <<  sizes[i]<< " " ; 
    }
    for (int i=0; i < price.size(); i++) {
        cout << price[i]  << endl;
    }

    cout << "Number of items: " << setw(itemwidth) << orderNumber << endl;
    cout << "Subtotal: "  << "$"  << fixed << setprecision (setpre) << setw (subwidth) << subtotal << endl;
    cout << "Tax (8.75%): " << "$"<< setw(taxwidth) << TAX * subtotal <<  endl;
    cout << "Total: " <<  "$" << setw(totalwidth) << (TAX *subtotal) + subtotal << endl;
    cout << endl;
    cout << "=========================================================" <<endl;     
    cout << endl;
}

class YogurtOrder {
public:
    YogurtOrder (); //default constructor
    YogurtOrder (string, string, string, string, double); //constructor with parameters: size, flavor1, flavor2, flavor3, and price
    string getSize ();
    string getMixedFlavor ();
    double getPrice ();
private:
    string size;
    string flavor1, flavor2, flavor3;
    double price;
};

YogurtOrder:: YogurtOrder() {}

YogurtOrder:: YogurtOrder (string s, string first, string second, string third, double p){
    s= size;
    first= flavor1;
    second= flavor2;
    third= flavor3;
    p= price;
}
string YogurtOrder:: getSize () {
    return size;
}

string YogurtOrder:: getMixedFlavor() { 

    return flavor1, flavor2, flavor3; 
}
double YogurtOrder:: getPrice() {

    return price; 
}

int main () {
    const double TAX= 0.0875;
    int setpre= 2;
    int totalwidth=15;
    int taxwidth= 9;
    int subwidth =12;
    int itemwidth= 6;
    //Print the welcome message
    printWelcomeMessage();
    // initialize the loop variables
    bool more_order = true;
    int orderNumber= 0;

    // varible for cost
    double subtotal= 0.;

    //variable for suze and flavors default intitialized to ""
    string yogurtSize, flavor1, flavor2, flavor3, order;
    //continye to get order until the user is done
    while (more_order) {
        //increment order number
        orderNumber++;
        //update the size and subtotal
        subtotal= subtotal +getYogurtSize(yogurtSize);
        //update the flavors
        getYogurtFlavors(flavor1, flavor2, flavor3);
        // print the current order
        printOrder (yogurtSize, flavor1, flavor2, flavor3, orderNumber);
        //determine whther or not to order more
        more_order= addAnotherOrderQ();
    }



        // Print out the subtotal, tax, and total
    vector <YogurtOrder> flavors; 
    printTotalCosts(subtotal, orderNumber);

    return 0;
}