Error: Infinite-loop when loading elements into vector

Question

void initializeVectorFromFile(vector<SInventory> & inven){

        ifstream initData("inventoryData.txt");

    if(!initData){

        cout << "File could not be accessed! Press any key to terminate program...";
        _getch();
        exit(1);

    }

    while(!initData.eof()){

        SInventory item;

        initData >> item.itemID;

        getline(initData,item.itemName);

        initData >> item.pOrdered
                 >> item.menufPrice
                 >> item.sellingPrice;
        item.pInStore = item.pOrdered;
        item.pSold = 0;

        inven.push_back(item);

        cout << item.itemID << endl;

    }

    cout << "File Read Success!" << endl;

    initData.close();
}

The .txt file I am reading from contain data structured in this order:

int
string
int double double

The output which is in the last line of the while-loop is repeated as the first itemID within the file. The initData stream does not read subsequent entries in the .txt file.

The homework tag is deprecated and shouldn't be used in new questions. — Kitsune, Dec 02 '12 at 22:04
@JerryCoffin This was an acceptable use in the following case, why can't I utilize this method for my example and what should I implement instead. Thanks http://stackoverflow.com/questions/9979894/using-vector-of-user-defined-class-type-objects — Michael, Dec 02 '12 at 22:06
@Michael: No, it wasn't really acceptable there either -- you may not have noticed the problem, but if you check carefully, you'll probably find your code said it read one more record than the file actually contained. As to what to do: see my answer for one possibility. — Jerry Coffin, Dec 02 '12 at 22:08

Jerry Coffin · Accepted Answer · 2012-12-02T22:09:55.980

Don't use while (!initData.eof()) -- ever. It's pretty much a guaranteed bug.

I'd start with code to read a single SInventor item from the file:

std::istream &operator>>(std::istream &initData, SInventor &item) { 
    initData >> item.itemID;

    getline(initData,item.itemName);

    initData >> item.pOrdered
             >> item.menufPrice
             >> item.sellingPrice;
    item.pInStore = item.pOrdered;
    item.pSold = 0;    
    return initData;
}

With that in place, it's probably easiest to just do without the rest of the function, and just initialize the vector directly:

std::ifstream infile("yourfile.txt");

std::vector<SInventor> inven((std::istream_iterator<SInventor>(infile)),
                              std::istream_iterator<SInventor>());

No loop, no mucked up test for EOF, etc., just a vector initialized from a pair of iterators.

score 1 · Answer 2 · answered Dec 02 '12 at 21:59

You can change your while loop to

SInventory item;
while(initData >> item.itemID){
    ...

or skip whitespace at the end of your while loop

    ws(initData);

or define an operator>>(istream&, SInventory &) and just do

SInventory item;
while(initData >> item){
    inven.push_back(item);
}

Error: Infinite-loop when loading elements into vector

2 Answers2