Reading from file problem

[jewel87]

Hello everyone,

I'm having a problem with reading data from file. In my form i have a function which should read the data from a file into a vector myProductList.

void __fastcall TForm1::FormCreate(TObject *Sender)
{
       myProductList.ReadData(i,size);
 
       myProductList.getProduct(i)->display(ProductIDLabel,
                                                     ProductNameLabel,
                                                     ProductWeightLabel,
                                                     PriceWithoutVATLabel,
                                                     PriceWithVATLabel,
                                                     ExpiryDateLabel,
                                                     AmountInStockLabel,
                                                     ReorderLimitLabel,
                                                     ProductCategoryLabel,
                                                     InputDateLabel,
                                                     DueDateLabel,
                                                     ManufacturerLabel,
                                                     ManufacturerAddressLabel,
                                                     ReorderStatus);
}
 

This is the ReadData() function in the myProductList class:

void ProductList :: ReadData(int &i, int &size)
{
    AnsiString ProductName;
    int ProductID;
    float Weight;
    float PriceWithoutVAT;
    float PriceWithVAT;
    AnsiString ExpiryDate;
    int AmountInStock;
    int ReorderLimit;
    AnsiString ProductCategory;
    AnsiString InputDate;
    AnsiString DueDate;
    AnsiString Manufacturer;
    AnsiString ManufacturerAddress;
 
        ifstream datafile("data.txt", ios::in);
        if (!datafile)
                {
                        exit(1);
                }
        else
        {
               while(!datafile.eof())
              {
                i++;
                size++;
                     datafile>>ProductID;
                     datafile>>ProductName.c_str();
                     datafile>>Weight;
                     datafile>>ExpiryDate.c_str();
                     datafile>>PriceWithoutVAT;
                     datafile>>PriceWithVAT;
                     datafile>>AmountInStock;
                     datafile>>ReorderLimit;
                     datafile>>ProductCategory.c_str();
                     datafile>>InputDate.c_str();
                     datafile>>DueDate.c_str();
                     datafile>>Manufacturer.c_str();
                     datafile>>ManufacturerAddress.c_str();
 
                     myProductList.push_back(Product(ProductName,
                                                    ProductID,
                                                    Weight,
                                                    PriceWithoutVAT,
                                                    PriceWithVAT,
                                                    ExpiryDate,
                                                    AmountInStock,
                                                    ReorderLimit,
                                                    ProductCategory,
                                                    InputDate,
                                                    DueDate,
                                                    Manufacturer,
                                                    ManufacturerAddress));
 
              };
 
                datafile.close();
 
                index=i;
                listsize=size;
        }
}
 

The other function - display() is working fine, but the problem is, when the file is empty, the program still reads some rubbish data from somewhere, i.e rubbish number values, and all the Strings are NULL. But if the file has some data, the program stucks and doesn't even open the form.
Could anyone help me, please?

[weaknessforcats]

datafile>>Produ ctName.c_str();
datafile>>Weigh t;
datafile>>Expir yDate.c_str();

I didn't look at all of the code but this is defintely a problem.

You need to datafile>>Produ ctName rather than
datafile>>Produ ctName.c_str().

The c_str() method makes a copy of the string. The string object was never used.

[jewel87]

I didn't look at all of the code but this is defintely a problem.

You need to datafile>>Produ ctName rather than
datafile>>Produ ctName.c_str().

The c_str() method makes a copy of the string. The string object was never used.

Thanks, I've tried to use char array instead, it removed part of the problems. I've been using c_str() because without it the compiler says it doesn't have operator >> for Strings.

Now, if the file it is reading is empty, it still tries to access it and reads some rubbish values from somewhere. Why my .eof condition is not working??? File is empty for sure..

[weaknessforcats]

I've been using c_str() because without it the compiler says it doesn't have operator >> for Strings.

You need to #include <string>.