input from a file into an array of class objects c++

Question

I am not sure how to input my data. Sorry I am a noob and the only examples I've found for something like this are way too complicated and I can't understand what is going on. I know this is not even close to being right but I have no idea how to set up the input from the file. My file data looks like this:

986  8
432  24
132  100
123  89
329  50
503  30
783  78
822  32
233  56
322  74

And my program so far looks like this:

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


// This program defines a class called Inventory that has itemnumber (which 
// contains the id number of a product) and numofitem (which contains the 
// quantity on hand of the corresponding product)as private data members.
// The program will read these values from a file and store them in an 
// array of objects (of type Inventory).  It will then print these values
// to the screen.

// Example: Given the following data file:
//     986 8
//     432 24
// This program reads these values into an array of objects and prints the
// following:
//     Item number 986 has 8 items in stock
//     Item number 432 has 24 items in stock


const int NUMOFPROD = 10;   // This holds the number of products a store sells

class Inventory
{
public:

   void getId(int item);      // This puts item in the private data member 
                              // itemnumber of the object that calls it.
   void getAmount(int num);   // This puts num in the private data member
                              // numofitem of the object that calls it.
   void display();            // This prints to the screen 
                              // the value of itemnumber and numofitem of the 
                              // object that calls it.



private:

   int  itemNumber;         // This is an id number of the product
   int  numOfItem;          // This is the number of items in stock 

};


int main()
{

   ifstream infile;       // Input file to read values into array
   infile.open("inventory.dat");

   // Fill in the code that declares an array of objects of class Inventory
   // called products. The array should be of size NUMOFPROD
   Inventory products[NUMOFPROD];

   int pos;                   // loop counter
   int id;                    // variable holding the id number
   int total;                 // variable holding the total for each id number

   // Fill in the code that will read inventory numbers and number of items  
   // from a file into the array of objects. There should be calls to both  
   // getId and getAmount member functions somewhere in this code.
   // Example: products[pos].getId(id); will be somewhere in this code
   pos = 0;
   while(NUMOFPROD > pos++ && infile >> products[pos])
   {
        id = products[pos];
        products[pos].getId(id);


       //products[pos].getAmount(total);
   }
    infile.close();
   // Fill in the code to print out the values (itemNumber and numOfItem) for 
   // each object in the array products.
   // This should be done by calling the member function display within a loop
   pos = 0;
   while(NUMOFPROD > pos++)
   {
       products[pos].display();
   }

   return 0;

}


// Write the implementations for all the member functions of the class.

void getId(int item)
{
    itemNumber = item;

}   
void getAmount(int num)
{
    numOfItem = num;
}
void display()
{
    cout << itemNumber << " ";
}

Answer 1

to input and from a file, do this:

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

int main()
{
    ifstream fin("YourTxtFile.txt");
    fin >> something //Fin acts just like your standard cin

    fin.close() //Don't forget to close the stream when you're done!
}

if you want to output to a file, do this:

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

int main()
{
    ofstream fout("YourTxtFile.txt");
    fout >> something //Fout acts just like your standard cout

    fout.close() //Don't forget to close the stream when you're done!
}

you can also do both at the same time!

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

int main()
{
    ifstream fin("YourTxtFile1.txt");
    fin >> something //Fin acts just like your standard cin

    fin.close() //Don't forget to close the stream when you're done!

    ofstream fout("YourTxtFile2.txt");
    fout >> something //Fout acts just like your standard cout

    fout.close() //Don't forget to close the stream when you're done!
}

Just to let you know, fin and fout can be called whatever you want.

If this post answers your question, please mark it as the answer.

Thanks