Static Members

Static members belong to the class itself instead of one object.

static_members.cpp

#include <iostream>

class Ticket {
private:
    static int nextId;
    int id;

public:
    Ticket() {
        id = nextId;
        nextId++;
    }

    int number() {
        return id;
    }

    static int nextNumber() {
        return nextId;
    }
};

int Ticket::nextId = 100;

int main() {
    int ticketCount = ;
    int lastNumber = 0;

    for (int i = 0; i < ticketCount; i++) {
        Ticket ticket;
        lastNumber = ticket.number();
    }

    std::cout << "ticketCount=" << ticketCount << std::endl;
    std::cout << "lastNumber=" << lastNumber << std::endl;
    std::cout << "nextNumber=" << Ticket::nextNumber() << std::endl;
    return 0;
}

#include <iostream>

class Ticket {
private:
    static int nextId;
    int id;

public:
    Ticket() {
        id = nextId;
        nextId++;
    }

    int number() {
        return id;
    }

    static int nextNumber() {
        return nextId;
    }
};

int Ticket::nextId = 100;

int main() {
    int ticketCount = ;
    int lastNumber = 0;

    for (int i = 0; i < ticketCount; i++) {
        Ticket ticket;
        lastNumber = ticket.number();
    }

    std::cout << "ticketCount=" << ticketCount << std::endl;
    std::cout << "lastNumber=" << lastNumber << std::endl;
    std::cout << "nextNumber=" << Ticket::nextNumber() << std::endl;
    return 0;
}

#include <iostream>

class Ticket {
private:
    static int nextId;
    int id;

public:
    Ticket() {
        id = nextId;
        nextId++;
    }

    int number() {
        return id;
    }

    static int nextNumber() {
        return nextId;
    }
};

int Ticket::nextId = 100;

int main() {
    int ticketCount = ;
    int lastNumber = 0;

    for (int i = 0; i < ticketCount; i++) {
        Ticket ticket;
        lastNumber = ticket.number();
    }

    std::cout << "ticketCount=" << ticketCount << std::endl;
    std::cout << "lastNumber=" << lastNumber << std::endl;
    std::cout << "nextNumber=" << Ticket::nextNumber() << std::endl;
    return 0;
}

static member A static member is shared by every object of the class.