C++ text file into array. (Newbie) - c++

Question

Hello everyone and sry in advance for the newbie question but i didn't find any topic specific to my problem. I have a text file of products as shown below:
//No. //Description //Price
100 Office_seat 102.99
200 Desk 224.99
300 Computer_desk 45.49
400 Desk_Lamb 23.99
500 Bookcase 89.49
i want to read it and save it in an array from which i will search for the Product_pin later and calculate the total price of a client's purchase.
tried something like the code i am posting but i think i am starting it all wrong. I would be gratefull for any advice.
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main()
{
ifstream file("Proionta.txt");
if(file.is_open())
{
string myArray[15];
for(int i=0;i<15;i++)
{
file>>myArray[i];
}
}
system ("pause");
}
Should i try to make a function to put the code in it?

Answer 1

Let's start out with the record modeling concept, then get primitive.
You want to model the text line as a record:
struct Record
{
unsigned int number;
std::string description;
double price;
};
The next step would be to overload operator>> for the Record:
struct Record
{
unsigned int number;
std::string description;
double price;
friend std::istream& operator>>(std::istream& input, Record& r);
};
std::istream& operator>>(std::istream& input, Record& r)
{
input >> r.number >> r.description >> r.price;
return input;
}
Using the above code, you can read in a file:
std::vector<Record> database;
Record r;
while (my_text_file >> r)
{
database.push_back(r);
}
Edit 1: Without struct
Let's say you don't know about how to use class or struct.
Each field can be read separately:
unsigned int number;
std::string description;
double price;
while (my_text_file >> number >> description >> price)
{
// Do something with number, description, price
}
Edit 2: Arrays vs. vector
Many assignments require you to do something with the data, like averages or searches. This usually requires you to save the data.
Two popular containers (from a student's point of view) are the array and std::vector.
Arrays are not a good choice, because with File I/O, you're never quite sure how many records there are and arrays like to be static in capacity (never changing). So you will need to do the resizing yourself:
static const unsigned int initial_capacity = 16U;
Record database[initial_capacity];
unsigned int capacity = initial_capacity;
Record r;
unsigned int items_read = 0;
while (my_text_file >> r)
{
if (items_read < capacity)
{
database[items_read] = r;
++items_read;
}
else
{
// Allocate new, larger array
// Copy items from old array to larger array.
// Update capacity variable.
// Delete old array
// Change database pointer to new array
}
}
A nice feature of std::vector is that you can access it like an array, and it will automatically increase in capacity as needed.