C++ program to enter records of multiple Objects and write to a FILE then display the chosen one

//program to read record of 5 books from user
//and write them in a file book.txt
//then read entire records from the file
//display the most expensive book

#include <iostream>
#include <fstream>
using namespace std;
class Book
{
  public:
    int id;
    char name[20];
    int nop;
    float price;
    void readRecord()
    {
      cout<<"Enter ID: ";
      cin>>id;
      cout<<"Enter book name: ";
      cin>>name;
      cout<<"Enter number of pages: ";
      cin>>nop;
      cout<<"Enter price: ";
      cin>>price;
    }
    void displayRecord()
    {
      cout<<endl<<"ID: "<<id;
      cout<<endl<<"Book Name: "<<name;
      cout<<endl<<"No. of Page: "<<nop;
      cout<<endl<<"Price: "<<price;
    }
    float GetMaxPrice()
    {
      return price;
    }
};
int main()
{
  Book b[5];
  int i;
  cout<<"Reading records of book: "<<endl;
  for(i=0;i<5;i++)
  {
    cout<<"Enter record "<<i+1<<":"<<endl;
    b[i].readRecord();
  }

  //writing to a file
  fstream file("book.txt",ios::out | ios::binary | ios::in);
  cout<<"Writing to a file.....";
  for(i=0;i<5;i++)
  {
    file.write((char*)&b[i],sizeof(b[i]));
  }
  cout<<"Records have been written to file...";

  //reading from file
  for(i=0;i<5;i++)
  {
    file.read((char*)&b[i],sizeof(b[i]));
    b[i].displayRecord();
  }

  //displaying the most expensive book
  float maxprice=b[0].price;
  for(i=1;i<5;i++)
  {
    if(maxprice<b[i].price)
        maxprice=b[i].price;
  }
  file.read((char*)&b[i],sizeof(b[i]));
  for(i=1;i<5;i++)
  {
    if(b[i].GetMaxPrice()==maxprice)
    {
      cout<<endl<<endl<<"The most expensive book is: "<<endl;
      b[i].displayRecord();
      break;
    }
    file.read((char*)&b[i],sizeof(b[i]));
  }
  file.close();
  return 0;
}