WHILE loop and data entry - c++

Question

I tried earlier to use a for loop to put data in but became too problematic. So I tried to use a while loop, it works but when I tried to debug it it continued to put -858993460 into every slot. The .dat file is in the right spot and opens.
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
struct record
{
int item_id;
string item_type;
float item_price;
int num_stock;
string item_title;
string item_author;
int year_published;
};
void read_all_records(record records[], int &valid_entries);
int num_inventory_of_type(record records[], string type, int &valid_entries);
const int max_array = 100;
int main()
{
int valid_entries = 0;
record records[max_array];
read_all_records(records, valid_entries);
cout << "Stock Report" << endl;
cout << "------------" << endl;
int book = num_inventory_of_type(records, "book", valid_entries);
cout << "Book's In Stock: " << book << endl;
int cd = num_inventory_of_type(records, "cd", valid_entries);
cout << "CD's In Stock: " << cd << endl;
int dvd = num_inventory_of_type(records, "dvd", valid_entries);
cout << "DVD's In Stock: " << dvd << endl;
return 0;
}
void read_all_records(record records[], int &valid_entries)
{
ifstream invfile;
invfile.open("inventory.dat");
if (!invfile.is_open())
{
cout<<"file open failed";
exit(1);
}
while(invfile.good() && valid_entries < max_array)
{
invfile >> records[valid_entries].item_id >> records[valid_entries].item_type
>> records[valid_entries].item_price >> records[valid_entries].num_stock
>> records[valid_entries].item_title >> records[valid_entries].item_author
>> records[valid_entries].year_published;
if(!invfile.good())
break;
valid_entries++;
}
invfile.close();
}
int num_inventory_of_type(record records[], string type, int &valid_entries)
{
int count = 0;
int holder = 0;
for (int count = 0; count<valid_entries; count++);
{
if (records[count].item_type == type)
{
holder+=records[count].num_stock;
}
}
return holder;
}
the .dat file is
123456
book
69.99
16
Problem_Solving_With_C++
Walter_Savitch
2011
123457
cd
9.99
32
Sigh_No_More
Mumford_and_Sons
2010
123458
dvd
17.99
15
Red_State
Kevin_Smith
2011
123459
cd
9.99
16
The_Church_Of_Rock_And_Roll
Foxy_Shazam
2012
123460
dvd
59.99
10
The_Walking_Dead_Season_1
Robert_Kirkman
2011
all are on new lines, no spaces.
Basically it should start, run the read_all_records function and put the .dat data into the array. However, I put the cout << records[count].item_id; in the while loop just to see if the data was actually going in, and I get -858993460 each time. After that it should run the next function 3 times and return how many of each books there are.

Answer 1

You used the integer type int on item_price. invfile >> records[count].item_price will then only extract 69 instead of 69.99, thus resulting in a error when you try to extract the year_published.
Use a float or double instead.
struct record
{
int item_id;
string item_type;
float item_price;
int num_stock;
string item_title;
string item_author;
int year_published;
};
/* skipped identical lines */
while(invfile.good() && count < max_array)
{
invfile >> records[count].item_id >> records[count].item_type
>> records[count].item_price >> records[count].num_stock
>> records[count].item_title >> records[count].item_author
>> records[count].year_published;
cout << records[count].item_price << endl;
if(!invfile.good())
break;
cout << records[count].item_id << endl;
count++;
}
invfile.close();
Note that you have an extra semicolon in for (int count = 0; count<max_array; count++);. I guess you didn't intend this, so remove it.

Answer 2

This isn't a direct answer to the problem, but perhaps it will go away after a refactoring:
std::istream& operator>>(std::istream& is, record& r) {
return is >> r.item_id >> r.item_type >> … >> r.year_published;
}
int main () {
if (std::ifstream invfile("inventory.dat")) {
std::vector<record> records((std::istream_iterator<record>(invfile)),
std::istream_iterator<record>());
num_inventory_of_type(records, "dvd");
num_inventory_of_type(records, "cd");
num_inventory_of_type(records, "book");
}
}
If you still want to print out each record as you read it, the code can be rearranged as follows:
std::vector<record> records;
for (std::istream_iterator<record> i(invfile);
i != std::istream_iterator<record>(); ++i)
{
records.push_back(*i);
std::cout << i->item_id << "\n";
}

Answer 3

You need to change int item_price; to a float so -> float item_price;
and as mentioned above you need to swap the count++; and cout << records[count].item_id line.
After these two changes it will work properly.
struct record
{
int item_id;
string item_type;
float item_price; // <--- Needs to be a float
int num_stock;
string item_title;
string item_author;
int year_published;
};
// This order is required because you are storing in the current 'count' record and then you need to print it. Then increment the count to store the next record
cout << records[count].item_id;
count++;