Untitled

#include <iostream>
#include <string>
#include <fstream>

using namespace std;

struct Institute
{
    Institute()
    {
        instituteID = "";
        instituteName = "";
        address = "";
        numberOfTeachers = 0;
        next = NULL;
        prev = NULL;
    }
    string instituteID;
    string instituteName;
    string deanName;
    int numberOfTeachers;
    string address;

    Institute *next;
    Institute *prev;
};

char validate()
{
    char answer = 'a';
    cout << "----------" << endl;
    while (answer > '9' || answer < '0')
    {
        cout << "Please enter a number: ";
        cin >> answer;
    }
    system("cls");
    return answer;
}

void printMenu()
{
    cout << "1. Show all institutes" << endl;
    cout << "2. Search institute by ID" << endl;
    cout << "3. Add new institute" << endl;
    cout << "4. Delete institute by ID" << endl;
    cout << "5. Search institute by Dean name" << endl;
    cout << "6. Count the number of institutes has more than 10 teachers" << endl;
    cout << "7. Sort institutes by decreasing the number of teachers" << endl;
    cout << "8. Add new institute satisfying position" << endl;
    cout << "9. Save to text file" << endl;
    cout << "0. Exit" << endl;
}

void printAllInstitutes(Institute *head)
{
    Institute *current = head;
    while (current != NULL)
    {
        cout << "Institute ID: " << current->instituteID << endl;
        cout << "Institute name: " << current->instituteName << endl;
        cout << "Dean name: " << current->deanName << endl;
        cout << "Number of teachers: " << current->numberOfTeachers << endl;
        cout << "Address: " << current->address << endl;
        current = current->next;
        cout << "-----------------" << endl;
    }
}

Institute *findInstituteByID(Institute *head, string instituteID, bool isPrintOut = true)
{
    Institute *current = head;
    while (current != NULL)
    {
        if (current->instituteID == instituteID)
        {
            if (isPrintOut)
            {
                cout << "Institute ID: " << current->instituteID << endl;
                cout << "Institute name: " << current->instituteName << endl;
                cout << "Dean name: " << current->deanName << endl;
                cout << "Number of teachers: " << current->numberOfTeachers << endl;
                cout << "Address: " << current->address << endl;
            }
            return current;
        }
        current = current->next;
    }
    if (isPrintOut)
    {
        cout << "Institute not found" << endl;
    }
    return NULL;
}

Institute *createInstitute()
{
    cin.clear();
    cin.ignore();
    Institute *newInstitute = new Institute();
    cout << "Institute ID: " << endl;
    getline(cin, newInstitute->instituteID);
    cout << "Institute name: " << endl;
    getline(cin, newInstitute->instituteName);
    cout << "Dean name: " << endl;
    getline(cin, newInstitute->deanName);
    cout << "Number of teachers: " << endl;
    cin >> newInstitute->numberOfTeachers;
    cin.clear();
    cin.ignore();
    cout << "Address: " << endl;
    getline(cin, newInstitute->address);
    return newInstitute;
}

void addInstituteStart(Institute **head, Institute *newInstitute)
{
    // Check exist
    if (findInstituteByID(*head, newInstitute->instituteID, false) != NULL)
    {
        cout << "Institute already exist" << endl;
    }
    else
    {
        newInstitute->next = *head;
        if (*head)
            (*head)->prev = newInstitute;
        (*head) = newInstitute;
    }
    return;
}

void deleteInstituteByID(Institute **head, string instituteID)
{
    Institute *institute = findInstituteByID(*head, instituteID, false);
    if (institute)
    {
        if (institute->prev == NULL)
        {
            (*head)->prev = NULL;
            (*head) = institute->next;
        }
        else if (institute->next == NULL)
        {
            institute->prev->next = NULL;
        }
        else
        {
            institute->prev->next = institute->next;
            institute->next->prev = institute->prev;
        }
        delete institute;
    }
    else
    {
        cout << "Institute not found" << endl;
    }
}

Institute *findInstituteByDeanName(Institute *head, string deanName, bool isPrintOut = true)
{
    Institute *current = head;
    while (current != NULL)
    {
        if (current->deanName == deanName)
        {
            if (isPrintOut)
            {
                cout << "Institute ID: " << current->instituteID << endl;
                cout << "Institute name: " << current->instituteName << endl;
                cout << "Dean name: " << current->deanName << endl;
                cout << "Number of teachers: " << current->numberOfTeachers << endl;
                cout << "Address: " << current->address << endl;
            }
            return current;
        }
        current = current->next;
    }
    if (isPrintOut)
    {
        cout << "Institute not found" << endl;
    }
    return NULL;
}

int countInstituteHasMoreThanNTeachers(Institute *head, int n)
{
    int count = 0;
    Institute *current = head;
    while (current != NULL)
    {
        if (current->numberOfTeachers > n)
        {
            count++;
        }
        current = current->next;
    }
    return count;
}

void sortInstituteByDecreasing(Institute **head)
{
    Institute *current = *head;
    if (current != NULL)
    {
        Institute *next = (*head)->next;
        while (current != NULL)
        {
            while (next != NULL)
            {
                if (current->numberOfTeachers < next->numberOfTeachers)
                {
                    Institute *temp = current;
                    current = next;
                    next = next->next;
                    current->prev = temp->prev;
                    current->next = temp;
                    temp->prev = current;
                    temp->next = next;
                    if (current->prev != NULL)
                    {
                        current->prev->next = current;
                    }
                    if (next != NULL)
                    {
                        next->prev = current;
                    }
                }
                else
                {
                    next = next->next;
                }
            }
            current = current->next;
            next = (current) ? current->next : NULL;
        }
    }
}

void addInstituteAfterSorting(Institute **head, Institute *newInstitute)
{
    Institute *current = (*head);
    if (current)
    {
        while (true)
        {
            if (current->numberOfTeachers < newInstitute->numberOfTeachers || current->next == NULL)
            {
                break;
            }
            current = current->next;
        }
        if (current->numberOfTeachers < newInstitute->numberOfTeachers)
        {
            if (current->prev)
            {
                current->prev->next = newInstitute;
            }
            else
            {
                (*head) = newInstitute;
            }
            newInstitute->prev = current->prev;
            newInstitute->next = current;
            current->prev = newInstitute;
        }
        else
        {
            current->next = newInstitute;
            newInstitute->prev = current;
        }
    }
    else
    {
        (*head) = newInstitute;
    }
}

void saveToFile(Institute *head)
{
    ofstream file;
    file.open("institutes.txt");
    Institute *current = head;
    while (current != NULL)
    {
        file << current->instituteID << endl;
        file << current->instituteName << endl;
        file << current->deanName << endl;
        file << current->numberOfTeachers << endl;
        file << current->address << endl;
        file << "--------" << endl;
        current = current->next;
    }
    file.close();
}

int main()
{
    // Declare variables
    Institute *head = NULL;
    string instituteID = "";
    string deanName = "";

    // Print menu
    char t = 'a';
    while (t != '0')
    {
        printMenu();
        t = validate();
        switch (t)
        {
        case '1':
            printAllInstitutes(head);
            break;
        case '2':
            cin.clear();
            cin.ignore();
            getline(cin, instituteID);
            findInstituteByID(head, instituteID);
            break;
        case '3':
            addInstituteStart(&head, createInstitute());
            cout << "Added new institute!" << endl;
            break;
        case '4':
            cin.clear();
            cin.ignore();
            getline(cin, instituteID);
            deleteInstituteByID(&head, instituteID);
            break;
        case '5':
            cin.clear();
            cin.ignore();
            getline(cin, deanName);
            findInstituteByDeanName(head, deanName);
            break;
        case '6':
            cout << "The number of institutes has more than 10 teachers: " << countInstituteHasMoreThanNTeachers(head, 10) << endl;
            break;
        case '7':
            sortInstituteByDecreasing(&head);
            cout << "Sorted institutes by decreasing the number of teachers..." << endl;
            break;
        case '8':
            addInstituteAfterSorting(&head, createInstitute());
            cout << "Added new institute satisfying position..." << endl;
            break;
        case '9':
            saveToFile(head);
            cout << "Saved to text file..." << endl;
            break;
        case '0':
            exit(0);
            break;
        }
        if (t != '0')
            system("pause");
    }
    delete head;
}