Reading books information from txt file in C++?

Question

I want to read books - their title, author and price from a txt file. The 3 properties of the book are separated by '|' - Title|Author|Book. However, I do not know exactly how to do this. I have the structure Book, with 3 elements. I want, for each line to read the book title, author and price, save them to the 3 variables of the structure respectively and print them on the console. I have tried to do this with the title only, but it print the whole line. I would like to ask how can I print for each books separately its author title and price?

Answer 1

The include libraries you will need, and your Book structure definition. Once you get to study slightly more advanced C++ topics you could learn how to overload friend functions for input and output streams to make your I/O operations self-contained for a Book object.

#include <iostream> ///< std::cout
#include <fstream>  ///< std::ifstream
#include <sstream>  ///< std::istringstream, std::string
#include <vector>   ///< std::vector

struct Book
{
    std::string title;  ///< title of the book
    std::string author; ///< author of the book
    std::string price;  ///< price of the book (TODO use float instead?)
    // TODO consider friend std::istream& operator>> for parsing input data
    // TODO consider friend std::ostream & operator<< for printing object
};

If you have a handle to your input file you could parse it like this. Read each line at a time. Do not read until input.eof() because it's wrong! Store each line into a temporary std::istringstream object for further parsing. Use the overloaded std::getline(stream, token, delimiter) with | to parse the data in the line, and save them directly into your temporary Book object. Finally, store the object into your vector if you want to be able to process them later, and optionally print them to the console.

void readBooks(std::ifstream& input, std::vector<Book>& books)
{
    std::string line;
    while (std::getline(input, line)) ///< while we have a line to parse
    {
        std::istringstream iss(line); ///< line to parse as sstream
        Book book; ///< temporary book object
        std::getline(iss, book.title, '|');
        std::getline(iss, book.author, '|');
        std::getline(iss, book.price, '|');
        books.push_back(book); ///< add book object into vector
        std::cout << "Title:  " << book.title << std::endl;
        std::cout << "Author: " << book.author << std::endl;
        std::cout << "Price:  " << book.price << std::endl << std::endl;
    }
}

int main()
{
    std::vector<Book> books;  ///< store each Book object
    std::ifstream input("books.txt");
    if (input.is_open())
    {
        readBooks(input, books); ///< read your books
    }
    return 0;
}

Tested with the following input file contents

Tales from Shakespeare (1807)|Shakespeare|6.74
The Jungle Book (1894)|Rudyard Kipling|9.99
Through the Looking-Glass (1871)|Lewis Carroll|12.97

Yielded the following results

Title:  Tales from Shakespeare (1807)
Author: Shakespeare
Price:  6.74

Title:  The Jungle Book (1894)
Author: Rudyard Kipling
Price:  9.99

Title:  Through the Looking-Glass (1871)
Author: Lewis Carroll
Price:  12.97

Answer 2

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

struct Book {
    string title;
    string author;
    string price;
};
void read_Books(std::ifstream&, Book&);

int main()
{
    ifstream p("books.txt", ios::in);
    Book a;
    read_Books(p, a);
    return 0;
}
void read_Books(std::ifstream& p, Book& ptstr) {
    while(p.is_open() && !p.eof()){
        getline(p, ptstr.title, '|');
        getline(p, ptstr.author, '|');
        getline(p, ptstr.price, '|');
        cout<<ptstr.title << ptstr.author << ptstr.price << std::endl;
        //The whole line is printed, it ought to be the title only
    }
}