First of all, I am new here to c++ and I'm trying to learn it. Also new to stackoverflow. Find it quite hard to be honest. If you have additional comments in terms of my code and how i can improve it, please let me know as I am still in the learning process.
ok I was I just creating a online booking system using object oriented programming.
Ok so the main issue is that I dont understand why system.setDisplay(1234); isn't printing anything. I have tried everything and just isn't adding up. OnlineBookingSystem is the class is being used to call setDisplay(id) which then invoked the display class. If you can help it would mean the world to me and the error i`m getting is:
runtime error: member call on null pointer of type 'User' (solution.cpp) SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior prog_joined.cpp:179:54
#include <vector>
#include <string>
#include <iostream>
#include <memory>
#include <queue>
using namespace std;
enum class BookGenre
{
Horror,Adventure,Romance,Comic
};
class Book
{
private:
BookGenre genre;
string title;
size_t id;
public:
Book(string title,size_t id,BookGenre genre):title(title),id(id),genre(genre){}
string getTitle(){return title;}
size_t getId(){return id;}
BookGenre getGenre(){return genre; }
};
class Library
{
private:
vector<shared_ptr<Book>> listOfBooks;
public:
Library(){};
void addBook(string title,size_t id,BookGenre genre)
{
listOfBooks.push_back(make_shared<Book>(title,id,genre));
}
shared_ptr<Book> getBook(size_t id)
{
for(auto&x:listOfBooks)
{
if(x->getId()==id)
{
return x;
}
}
return nullptr;
}
void removeBook(size_t id)
{
for(auto it=listOfBooks.begin();it!=listOfBooks.end();it++)
{
if((*it)->getId()==id)
{
listOfBooks.erase(it);
}
}
}
};
class User
{
protected:
size_t id;
string username;
public:
User(size_t id,string username):id(id),username(username)
{
}
virtual ~User(){}
size_t getId(){return id;}
string getUsername(){return username;}
};
class Employee:public User{
private:
double salary;
public:
Employee(size_t id,string username,double salary):User(id,username),salary(salary)
{
}
void setSalary(double salary)
{
this->salary=salary;
}
double getSalary(){return salary;}
};
class Customer:public User{
private:
bool membership;
public:
Customer(size_t id,string username):User(id,username)
{
membership=false;
}
void setMemberActive()
{
membership=true;
}
bool isMemberActive()
{
return membership;
}
};
class UserManager
{
private:
vector<shared_ptr<User>>listOfUsers;
queue<shared_ptr<Customer>>queue;
public:
UserManager()
{
}
void addCustomer(size_t id,string username)
{
listOfUsers.push_back(make_shared<Customer>(id,username));
}
void removeCustomer(string username)
{
for(auto it=listOfUsers.begin();it!=listOfUsers.end();it++)
{
if(dynamic_pointer_cast<Customer>(*it))
{
if((*it)->getUsername()==username)
{
listOfUsers.erase(it);
}
}
}
}
shared_ptr<Customer> getCustomer(string username)
{
for(auto it=listOfUsers.begin();it!=listOfUsers.end();it++)
{
if(dynamic_pointer_cast<Customer>(*it))
{
if((*it)->getUsername()==username)
{
return dynamic_pointer_cast<Customer>(*it);
}
}
}
return nullptr;
}
void addToQueue(string username)
{
queue.push(getCustomer(username));
}
void removeCurrentCustomer()
{
queue.pop();
}
shared_ptr<Customer> getNextCustomer()
{
if(queue.empty())
{
return nullptr;
}
return queue.front();
}
/*
same process for user;
*/
};
class Display
{
private:
shared_ptr<Customer> m_customer;
shared_ptr<Book> m_book;
public:
Display(shared_ptr<Customer> _customer,shared_ptr<Book> _book ):m_customer(_customer),m_book(_book)
{
}
shared_ptr<Customer> getUser(){return m_customer;}
shared_ptr<Book> getBook(){return m_book;}
void displayInfo()
{
cout<<"Customer username: "<<m_customer->getUsername()<<endl;
cout<<"Member Active: "<<m_customer->isMemberActive();
cout<<"book id: "<<m_book->getId()<<endl;
cout<<"book title: "<< m_book->getTitle()<<endl;
}
};
class OnlineBookingSystem
{
private:
UserManager manager;
Library library;
shared_ptr<Display>display;
public:
OnlineBookingSystem()
{
UserManager manager;
Library library;
this->manager=manager;
this->library=library;
this->display=nullptr;
}
Library getLibrary()
{
return library;
}
UserManager getUserManager()
{
return manager;
}
void setDisplay(size_t id)
{
display=make_shared<Display>( manager.getNextCustomer(),library.getBook(id));
display->displayInfo();
}
shared_ptr<Display> getDisplay()
{
return this->display;
}
};
int main()
{
OnlineBookingSystem system;
auto lib=system.getLibrary();
lib.addBook("Adventure of Pablo",1234,BookGenre::Adventure);
auto manager=system.getUserManager();
manager.addCustomer(2020,"Michael");
auto _customer= manager.getCustomer("Michael");
_customer->setMemberActive();
manager.addToQueue("Michael");
system.setDisplay(1234);
return 0;
}
