Using objects of a class in another class?

Question

I have created a class called Book and it can have many Books. But I want to create a class shelf which can contain only 10 of Books if it is greater than than 10 ten it should print Error Message! But I cannot think of a way to make class shelf. So far I have done this :

#include <iostream>
#include <string>
using namespace std;

class Book{
private:
    string bookName;
    int pNum;

public:
    Book();
    Book(string tempName, int tNum){
        setName(tempName);
        setPageNum(tNum);
    }

    void setName(string bName){
    bookName = bName;
    }



    void setPageNum(int tempNum){
        pNum = tempNum;
    }

    string getName(){
     return bookName;

         }
    int getPageNum(){
        return pNum;

         }
};

class Shelf{
    public:
    Book nBook[10];
    void addbook();
void Book::addbook(Book nBook[10])
{
    for(int i = 0; i<10; i++)
        nBook[i] = nBook[i].setName(string bName)

}


};
int main(){

    Book math = Book("math", 500);
    Book abcd = Book("abcd", 501);


    cout << English.getName() <<" "<<English.getPageNum()<<endl;
    cout << German.getName() <<" "<<German.getPageNum()<<endl;


}

how should i use std vectors? i have completely no idea to use vectors? — Hasnain Ali
– Hasnain Ali, Commented Apr 12, 2015 at 3:24
I recommend finding some introductory material on them to read. They are one of the most practical things in the standard library IMO. — Qaz
– Qaz, Commented Apr 12, 2015 at 3:40
nBook[i] = nBook[i].setName(string bName) This line won't compile. setName doesn't return anything, and that is not how to pass a parameter. I would expect a function called addbook would only add 1 book, not several. — Neil Kirk
– Neil Kirk, Commented Apr 12, 2015 at 4:08
Also Book math = Book("math", 500); is a waste, just do Book math("math", 500); — paulm
– paulm, Commented Apr 12, 2015 at 12:33

StefanW · Accepted Answer · 2015-04-12 12:29:29Z

2

You can use the standard vector class to store the Book objects in the shelf. In the example below, the book object will be copied when added to the Shelf

#include <vector>
using namespace std;
class Shelf{
public:
  vector<Book> books;

  bool addbook(Book book)
  {
    if(books.size() > 10) 
      {
        return false;
      }
    else 
      {
        books.push_back(book);
        return true;
      }
  }
};

answered Apr 12, 2015 at 12:29

StefanW

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Comments

Lev Izraelit · Accepted Answer · 2015-04-12 04:40:25Z

1

There are many ways to implement this. Note the default constructor of class Book. Let me know if you have any questions.

#include <iostream>
#include <string>
using namespace std;

class Book{
private:
    string bookName;
    int pNum;

public:
    Book(){
    }
    Book(string tempName, int tNum){
        setName(tempName);
        setPageNum(tNum);
    }

    void setName(string bName){
    bookName = bName;
    }

    void setPageNum(int tempNum){
        pNum = tempNum;
    }

    string getName(){
     return bookName;

    }
    int getPageNum(){
        return pNum;

    }
};

class Shelf{
    public:
    Book nBook[10];
    int numberOfBooks;
    void addbook(Book);

    Shelf()
    {
       numberOfBooks = 0;
    }

    bool addBook(Book newBook)
    {
        if (numberOfBooks == 10)
        {
            return false;
        }
        else
        {
            nBook[numberOfBooks] = newBook;
            numberOfBooks++;
            return true;
        }
    }


};
int main(){

    Book English = Book("math", 500);
    Book German = Book("abcd", 501);


    Shelf bookShelf = Shelf();

    bookShelf.addBook(English);

}

edited Apr 12, 2015 at 4:40

answered Apr 12, 2015 at 4:27

Lev Izraelit

5324 silver badges15 bronze badges

4 Comments

Neil Kirk Over a year ago

What's the point of copyBook? Just use the copy constructor or assignment operator, which is generated for you automatically.

Neil Kirk Over a year ago

Three is no need to use new in this code, which is leaking memory as you have no delete.

Neil Kirk Over a year ago

Book nBook[10]; ... nBook[numberOfBooks - 1] = newBook;

Lev Izraelit Over a year ago

@Hasnain It works for me. I just tried the code on cpp.sh I just added the following in main: for (int i = 0; i < 11; i++) cout << bookShelf.addBook(English) << endl;

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