Mid I, Bus

#include <iostream>
#include <iomanip>
#include <string>

using namespace std;

class Bus{
private:
    static int a;
    int id, capacity, available_seats;
    string departure_city, arrival_city;

public:
    Bus(): id(a), capacity(0), available_seats(0), departure_city("N/A"), arrival_city("N/A"){++a;}
    ~Bus(){}
    void readData();
    void updateSeats(int n);
    void showData();
    string getDep();
    string getArr();
    int getAvail();
};

int Bus::a = 101;

void showCategories();
void findBus(Bus *B, int nb, string departure, string arrival, int nt);

int main(){

    int nb, i, nt;
    string departure, arrival;

    cout << "Bangla-Indo Joint Transportation Venture Limited" << endl;
    cout << "Phase I : Bus Registration" << endl;
    cout << "Enter number of buses: ";
    cin >> nb;

    Bus B[nb];

    for(i = 0; i < nb; i++){
        cout << "Enter info of Bus " << i + 1 << ": ";
        B[i].readData();
    }

    cout << "Phase II : Tickets Sale" << endl;

    do{
        cout << "Enter Dep. and Arr. City and tickets: ";

        cin >> departure >> arrival >> nt;

        findBus(&B[0], nb, departure, arrival, nt);
    }
    while(departure != "N/A" && arrival != "N/A" && nt != 0);

    cout << "Phase III : Final Reservation Status" << endl;

    showCategories();

    for(i = 0; i < nb; i++)
        B[i].showData();

    cout << "Bye Bye. Have a safe trip!" << endl;

    return 0;
}


void showCategories(){
    cout << right << setw(6) << "BUS ID" << " " << left << setw(12) << "DEPARTURE" << left << setw(12) << "ARRIVAL" << right << setw(10) << "CAPACITY" << right << setw(11) << "AVAILABLE" << endl;
    return;
}


void Bus::readData(){
    cin >> departure_city >> arrival_city >> capacity >> available_seats;
    return;
}


void Bus::updateSeats(int n){
    available_seats -= n;
    cout << "RESERVATIONS CONFIRMED" << endl;
    return;
}


void Bus::showData(){
    cout << right << setw(6) << id << " " << left << setw(12) << departure_city << left << setw(12) << arrival_city << right << setw(10) << capacity << right << setw(11) << available_seats << endl;
    return;
}


string Bus::getDep(){
    return departure_city;
}


string Bus::getArr(){
    return arrival_city;
}


int Bus::getAvail(){
    return available_seats;
}


void findBus(Bus *B, int nb, string departure, string arrival, int nt){
    int i;
    for(i = 0; i < nb; i++)
            if(departure == B[i].getDep() && arrival == B[i].getArr()){
                if(nt <= B[i].getAvail()){
                    B[i].updateSeats(nt);
                    break;
                }
                else
                    cout << "NOT ENOUGH SEATS. TRY LATER!" << endl;
            }
}