I am struggling with this program trying to change it from structured C++ code to an object oriented code. if anyone could offer help that would be great. the code is:

   // C++ program to implement the program
// that illustrates Online shopping
#include <string>
#include <iostream>
#include <map>
using namespace std;

char c1, confirm_quantity;
float quantity;
int selectedNum;
double total_amount = 0;
int flag = 0;

// Stores items with their corresponding
// price
map<string, double> items = {
{ "Samsung", 15000 },
{ "Redmi", 12000 },
{ "Apple", 100000 },
{ "Macbook", 250000 },
{ "HP", 40000 },
{ "Lenovo", 35000 },
{ "C", 1000 },
{ "C++", 3000 },
{ "Java", 4000 },
{ "Python", 3500 }
};

// Stores the selected items with
// their quantity
map<string, int> selected_items;

// Function to print the bill after shopping
// is completed prints the items, quantity,
// their cost along with total amount
void printBill(map<string, double> items,
        map<string, int> selected_items,
        float total_amount)
{
    cout << "Item    "
    << "Quantity     "
    << "Cost\n";

for (auto j = selected_items.begin();
    j != selected_items.end(); j++) {
    cout << j->first << "    ";
    cout << j->second << "       ";
    cout << (selected_items[j->first])
                * (items[j->first])
        << endl;
}

cout << "-----------------------"
    << "-------------\n";
cout << "Total amount:           "
    << total_amount << endl;
cout << "-----------------------"
    << "-------------\n";
cout << "*****THANK YOU && HAPPY"
    << " ONLINE SHOPPING*****";
}

// Function to ask the basic details of
// any customer
void customerDetails()
{

cout << "Enter your name: ";
string customer_name;
getline(cin, customer_name);

cout << "WELCOME ";
for (int i = 0;
    i < customer_name.length();
    i++) {
    cout << char(toupper(
        customer_name[i]));
}
cout << "\n";
}

// showMenu() is to print the
// menu to the user
void showMenu()
{
cout << "Menu\n";
cout << "= = = = = = = = "
    << " = = = = = \n";
cout << "1.Mobile\n2.laptop\n3"
    << ".Computer courses\n";
cout << "= = = = = = = = "
    << " = = = = = \n";
}

// Function to display the mobile products
void showMobileMenu()
{
cout << "- - - - - - - - - - -"
    << " - -\nItem   Cost\n";
cout << "1.Samsung Rs.15, 000/-\n";
cout << "2.Redmi Rs.12, 000/-\n";
cout << "3.Apple Rs.1, 00, 000/-\n";
cout << "- - - - - - - - - - - - -\n";
}

// Function to display Laptop products
void showLaptopMenu()
{
cout << "- - - - - - - - - - -"
    << " - -\nItem   Cost\n";
cout << "1.Macbook Rs.2, 00, 000/-\n";
cout << "2.HP    Rs.40, 000/-\n";
cout << "3.Lenovo Rs.35, 000/-\n";
cout << "- - - - - - - - - - - - -\n";
}

// if the user selects computer courses,
// then courses list will be displayed
void showComputerCourseMenu()
{
cout << "- - - - - - - - - - "
    << " - -\nItem   Cost\n";
cout << "1.C     Rs.1, 000/-\n";
cout << "2.C++   Rs.3, 000/-\n";
cout << "3.Java  Rs.4, 000/-\n";
cout << "4.Python Rs.3, 500/-\n";
cout << "- - - - - - - - - - - - -\n";
}

// Function to display the mobile category
void selectedMobile()
{
cout << "Do you wish to continue?(for yes press (Y/y ), ";
cout << " if no press other letter ): ";
cin >> c1;

if (c1 == 'Y' || c1 == 'y') {
    cout << "Enter respective number: ";
    cin >> selectedNum;

    if (selectedNum == 1
        || selectedNum == 2
        || selectedNum == 3) {

        // Selected Samsung
        if (selectedNum == 1) {

            cout << "selected Samsung\n";
            do {
                cout << "Quantity: ";

                cin >> quantity;

                cout << "You have selected Samsung - "
                    << quantity << endl;
                cout << "Are you sure?"
                    << "(for yes press (Y/y ), "
                    << " if no press other letter): ";

                cin >> confirm_quantity;

            } while ((confirm_quantity != 'y'
                    && confirm_quantity != 'Y')
                    || (quantity < 0)
                    || (ceil(quantity) != floor(quantity)));

            if (confirm_quantity == 'y'
                || confirm_quantity == 'Y') {
                total_amount += quantity
                                * items["Samsung"];
                selected_items["Samsung"] = quantity;
                cout << "amount = "
                    << total_amount << endl;
            }
        }

        // Selected Redmi
        if (selectedNum == 2) {

            cout << "selected Redmi\n";

            do {
                cout << "Quantity: ";
                cin >> quantity;
                cout << "You have selec"
                    << "ted Redmi - "
                    << quantity << endl;
                cout << "Are you sure?(f"
                    << "or yes press (Y/y ), "
                    << " if no press other letter ): ";
                cin >> confirm_quantity;
            } while ((confirm_quantity != 'y'
                    && confirm_quantity != 'Y')
                    || (quantity < 0)
                    || (ceil(quantity)
                        != floor(quantity)));

            if (confirm_quantity == 'y'
                || confirm_quantity == 'Y') {

                total_amount += quantity
                                * items["Redmi"];
                selected_items["Redmi"] = quantity;
                cout << "amount = "
                    << total_amount << endl;
            }
        }

        // Selected Apple
        if (selectedNum == 3) {

            cout << "You have selected Apple\n";

            do {
                cout << "Quantity: ";
                cin >> quantity;
                cout << "You have selected"
                    << " Apple - "
                    << quantity
                    << endl;
                cout << "Are you sure?"
                    << "(for yes press (Y/y )"
                    << ", if no press other letter ): ";
                cin >> confirm_quantity;
            } while ((confirm_quantity != 'y'
                    && confirm_quantity != 'Y')
                    || (quantity < 0)
                    || (ceil(quantity)
                        != floor(quantity)));

            if (confirm_quantity == 'y'
                || confirm_quantity == 'Y') {
                total_amount += quantity
                                * items["Apple"];
                selected_items["Apple"] = quantity;
                cout << "amount = "
                    << total_amount
                    << endl;
            }
        }
    }
    else {
        flag = 1;
    }
}
else {
    flag = 1;
}
}

// If Laptop category is selected
void selectedLaptop()
{
    cout << "Do you wish to continue?"
    << "(for yes press (Y/y ), "
    << "if no press other letter): ";
cin >> c1;
if (c1 == 'Y' || c1 == 'y') {

    cout << "Enter respective number: ";
    cin >> selectedNum;

    if (selectedNum == 1
        || selectedNum == 2
        || selectedNum == 3) {

        // selected Macbook
        if (selectedNum == 1) {
            cout << "selected Macbook\n";
            do {

                cout << "Quantity: ";
                cin >> quantity;

                cout << "You have selected"
                    << " Macbook - "
                    << quantity << endl;
                cout << "Are you sure?"
                    << "(for yes press (Y/y ), "
                    << " if no press other letter ): ";
                cin >> confirm_quantity;
            } while ((confirm_quantity != 'y'
                    && confirm_quantity != 'Y')
                    || (quantity < 0)
                    || (ceil(quantity)
                        != floor(quantity)));

            if (confirm_quantity == 'y'
                || confirm_quantity == 'Y') {
                total_amount += quantity
                                * items["Macbook"];
                selected_items["Macbook"] = quantity;
                cout << "amount = "
                    << total_amount
                    << endl;
            }
        }

        // selected HP
        if (selectedNum == 2) {
            cout << "selected HP\n";
            do {
                cout << "Quantity: ";
                cin >> quantity;
                cout << "You have selected"
                    << " HP - "
                    << quantity << endl;
                cout << "Are you sure?"
                    << "(for yes press (Y/y ), "
                    << " if no press other letter ): ";
                cin >> confirm_quantity;
            } while ((confirm_quantity
                        != 'y'
                    && confirm_quantity != 'Y')
                    || (quantity < 0)
                    || (ceil(quantity)
                        != floor(quantity)));

            if (confirm_quantity == 'y'
                || confirm_quantity == 'Y') {
                total_amount += quantity
                                * items["HP"];
                selected_items["HP"] = quantity;
                cout << "amount = "
                    << total_amount
                    << endl;
            }
        }

        // selected Lenovo
        if (selectedNum == 3) {
            cout << "selected Lenovo\n";
            do {

                cout << "Quantity: ";
                cin >> quantity;

                cout << "You have selected"
                        " Lenovo - "
                    << quantity << endl;
                cout << "Are you sure?"
                    << "(for yes press (Y/y ), "
                    << "if no press other letter ): ";
                cin >> confirm_quantity;
            } while ((confirm_quantity != 'y'
                    && confirm_quantity != 'Y')
                    || (quantity < 0)
                    || (ceil(quantity)
                        != floor(quantity)));

            if (confirm_quantity == 'y'
                || confirm_quantity == 'Y') {
                total_amount += quantity
                                * items["Lenovo"];
                selected_items["Lenovo"] = quantity;
                cout << "amount = "
                    << total_amount
                    << endl;
            }
        }
    }
    else {
        flag = 1;
    }
}
else {
    flag = 1;
}
}

// If computer course
// category is selected
void selectedCourses()
{
    cout << "Do you wish to continue?"
    << "(for yes press (Y/y ), "
    << " if no press other letter ): ";
    cin >> c1;
    if (c1 == 'Y' || c1 == 'y') {
    cout << "Enter the respective number: ";
    cin >> selectedNum;
        if (selectedNum == 1
           || selectedNum == 2
        || selectedNum == 3
        || selectedNum == 4) {

        // selected C
        if (selectedNum == 1) {
            cout << "selected C Language"
                << " course\n";
            total_amount += items["C"];
            selected_items["C"]++;
            cout << "amount = "
                << total_amount
                << endl;
        }

        // selected C++
        if (selectedNum == 2) {
            cout << "selected C++ Language course\n";
            total_amount += items["C++"];
            selected_items["C++"]++;
            cout << "amount = " << total_amount << endl;
        }

        // selected Java
        if (selectedNum == 3) {
            cout << "selected Java Language course\n";
            total_amount += items["Java"];
            selected_items["Java"]++;
            cout << "amount = " << total_amount << endl;
        }

        // selected python
        if (selectedNum == 4) {
            cout << "selected Python"
                << " Language course\n";
            total_amount += items["Python"];
            selected_items["Python"]++;
            cout << "amount = "
                << total_amount
                << endl;
        }
    }
    else {
        flag = 1;
    }
}
else {
    flag = 1;
}
}

// Driver code
int main()
{
    // function call
customerDetails();

do {
    showMenu();
    cout << "Do you wish to continue?"
        << "(for yes press (Y/y ), "
        << " if no press other letter ): ";
    char c;
    cin >> c;
    if (c == 'Y' || c == 'y') {
        cout << "Enter respective number: ";
        int num;
        cin >> num;
        if (num == 1 || num == 2
            || num == 3) {
            switch (num) {
            case 1:

                // For Mobile
                showMobileMenu();
                selectedMobile();
                break;

            case 2:

                // For Laptop
                showLaptopMenu();
                selectedLaptop();
                break;

            case 3:

                // For computer course
                showComputerCourseMenu();
                selectedCourses();
                break;
            }
        }
        else {
            flag = 1;
        }
    }
    else {
        flag = 1;
    }

} while (flag == 0);

// print bill
printBill(items, selected_items,
        total_amount);
}

sit down and think about what you want to do, what the program's structure will be as an object oriented system.
Don't just mindlessly start coding.

And that includes homework assignments.

commented: "You want to go home and rethink your design." "I wanna go home and rethink my design." +16
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