how to insert data from a text file into an array of struct

Question

I need to read data from a text file, and insert the data in an array of struct. The data file is in the following format:

productname  price  quantity

my main concern is to read the product name, which consist of one, and two words. Should I approach product name as a c-string or as a string literal?

any help appreciated

#include <iostream>
#include <fstream>

using namespace std;

const int SIZE = 15; //drink name char size
const int ITEMS = 5; //number of products

struct drinks
{
       char drinkName[SIZE];
       float drinkPrice;
       int drinkQuantity;
};      


int main()
{
    //array to store drinks
    drinks softDrinks[ITEMS];

    //opening file
    ifstream inFile;
    inFile.open("drinks.txt");

    char ch;
    int count = 0; //while loop counter


    if(inFile)
    {
         while(inFile.get(ch))
         {
             //if(isalpha(ch)) { softDrinks[count].drinkName += ch; }
             //if(isdigit(ch)) { softDrinks[count].drinkPrice += ch; }
             cout << ch;

         }
         cout << endl;
         count++;  
    }
    else
    {
        cout << "Error opening file!\n";
        system("pause");
        exit(0);
    }

    system("pause");
    return 0;
}

Kerrek SB · Accepted Answer · 2011-12-03 02:26:38Z

3

Since you ask for "any help", here's my view: Forget everything you wrote, and use C++:

#include <fstream>   // for std::ifstream
#include <sstream>   // for std::istringstream
#include <string>    // for std::string and std::getline

int main()
{
    std::ifstream infile("thefile.txt");
    std::string line;

    while (std::getline(infile, line))
    {
        std::istringstream iss(line);

        std::string name;
        double price;
        int qty;

        if (iss >> name >> price >> qty)
        {
            std::cout << "Product '" << name << "': " << qty << " units, " << price << " each.\n";
        }
        else
        {
          // error processing that line
        }
    }
}

You could store each line of data in a std::tuple<std::string, int, double>, for example, and then put those into a std::vector as you go along.

edited Dec 3, 2011 at 2:26

answered Dec 3, 2011 at 2:18

Kerrek SB

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6 Comments

FailedDev Over a year ago

+1 for Forget everything you wrote, and use C++. How can you make someone forget? :)

Kerrek SB Over a year ago

@FailedDev: I wish I knew. My basic rule is like this: "If you're using pointers, new, or using namespace std;, You're Doing it Wrong." Take it for what it's worth. I guess "fixed-sized arrays with magic constants" should go in there, too.

FailedDev Over a year ago

Also best loc I have ever seen #define private public - This in product code :)

Kerrek SB Over a year ago

@FailedDev: Haha, best way to make those pesky compiler errors go away. Me, I prefer #define abusing using.

miatech Over a year ago

yeah, this is great if all lines are the same format, but some lines contain a product of one word, and others contain a product of two words. so this: "if (iss >> name >> price >> qty)" would not give me the desired result

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