Using int alongside string and getline without errors - c++

Question

I'm creating a program that reads the author, title, and number of volumes from a file and prints out labels,
(ex.
Adams
A Complete History of the World
Volume 1 of 10
Adams
A Complete History of the World
Volume 2 of 10 etc.)
To make it read properly and not infinitely loop, I had to change all of my variable to string. However, for future reference to the volume number, I need it to be int so I can compare the amount.
My ideas for furthering the code with a do-while loop are commented in to show why I'd like vnum to have int value.
#include <fstream>
#include <iostream>
#include <string>
using namespace std;
int main()
{
ifstream fin;
string author;
string title;
string vnum;
int counter=1;
fin.open("publish.txt", ios::in);
while (!fin.eof())
{
getline(fin, author);
getline(fin, title);
getline(fin, vnum);
//do
//{
cout << author << endl;
cout << title << endl;
cout << "Volume " << counter << " of " << vnum << endl;
cout << endl;
//counter++;
//} while(counter < vnum);
}
fin.close();
return 0;
}
File I'm reading from:
Adams
A Complete History of the World
10
Samuels
My Life of Crime
2
Baum
Wizard Stories
6

Answer 1

First of all, avoid use of
while (!fin.eof())
See Why is “while ( !feof (file) )” always wrong? to understand the problems it would cause.
Coming to your task, I would suggest:
Create a struct to hold the data.
Add a function to read all the members of the struct from a std::istream.
Add a function to write all the members of the struct to a std::ostream.
Simplify main to use the above.
Here's what I suggest:
struct Book
{
std::string author;
std::string title;
int volume;
};
std::istream& operator>>(std::istream& in, Book& book);
std::ostream& operator<<(std::ostream& out, Book const& book);
That will help simplify main to:
int main()
{
ifstream fin;
Book book;
// Not sure why you would need this anymore.
int counter=1;
fin.open("publish.txt", ios::in);
while ( fin >> book )
{
cout << book;
++counter;
}
return 0;
}
The functions to read and write a Book can be:
std::istream& operator>>(std::istream& in, Book& book)
{
// Read the author
getline(in, book.author);
// Read the title
getline(in. book.title);
// Read the volume
in >> book.volume;
// Ignore rest of the line.
in.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
return in;
}
std::ostream& operator<<(std::ostream& out, Book const& book)
{
out << book.author << std::endl;
out << book.title << std::endl;
out << book.volume << std::endl;
return out;
}