C++ run error: pointer being freed was not allocated [closed] - c++

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Closed 10 years ago.
I'm learning c++ and am working on a program that keeps giving me a 'pointer being freed was not allocated' error. It's a grocery store program that inputs data from a txt file, then user can enter item# & qty. I've read through similar questions but what's throwing me off is the 'pointer' issue. I would appreciate if someone could take a look and help me out. I'm using Netbeans IDE 7.2 on a Mac.
I'll just post the whole piece I have so far. Thx.
#include <iostream>
#include <fstream>
#include <string>
#include <vector>
using namespace std;
class Product
{
public:
// PLU Code
int getiPluCode()
{
return iPluCode;
}
void setiPluCode( int iTempPluCode)
{
iPluCode = iTempPluCode;
}
// Description
string getsDescription()
{
return sDescription;
}
void setsDescription( string sTempDescription)
{
sDescription = sTempDescription;
}
// Price
double getdPrice()
{
return dPrice;
}
void setdPrice( double dTempPrice)
{
dPrice = dTempPrice;
}
// Type..weight or unit
int getiType()
{
return iType;
}
void setiType( int iTempType)
{
iType = iTempType;
}
// Inventory quantity
double getdInventory()
{
return dInventory;
}
void setdInventory( double dTempInventory)
{
dInventory = dTempInventory;
}
private:
int iPluCode;
string sDescription;
double dPrice;
int iType;
double dInventory;
};
int main ()
{
Product paInventory[21]; // Create inventory array
Product paPurchase[21]; // Create customer purchase array
// Constructor to open inventory input file
ifstream InputInventory ("inventory.txt", ios::in);
//If ifstream could not open the file
if (!InputInventory)
{
cerr << "File could not be opened" << endl;
exit (1);
}//end if
int x = 0;
while (!InputInventory.eof () )
{
int iTempPluCode;
string sTempDescription;
double dTempPrice;
int iTempType;
double dTempInventory;
InputInventory >> iTempPluCode >> sTempDescription >> dTempPrice >> iTempType >> dTempInventory;
paInventory[x].setiPluCode(iTempPluCode);
paInventory[x].setsDescription(sTempDescription);
paInventory[x].setdPrice(dTempPrice);
paInventory[x].setiType(iTempType);
paInventory[x].setdInventory(dTempInventory);
x++;
}
bool bQuit = false;
//CREATE MY TOTAL VARIABLE HERE!
int iUserItemCount = 0;
do
{
int iUserPLUCode;
double dUserAmount;
double dAmountAvailable;
int iProductIndex = -1;
//CREATE MY SUBTOTAL VARIABLE HERE!
while(iProductIndex == -1)
{
cout<<"Please enter the PLU Code of the product."<< endl;
cin>>iUserPLUCode;
for(int i = 0; i < 21; i++)
{
if(iUserPLUCode == paInventory[i].getiPluCode())
{
dAmountAvailable = paInventory[i].getdInventory();
iProductIndex = i;
}
}
//PLU code entry validation
if(iProductIndex == -1)
{
cout << "You have entered an invalid PLU Code.";
}
}
cout<<"Enter the quantity to buy.\n"<< "There are "<< dAmountAvailable << "available.\n";
cin>> dUserAmount;
while(dUserAmount > dAmountAvailable)
{
cout<<"That's too many, please try again";
cin>>dUserAmount;
}
paPurchase[iUserItemCount].setiPluCode(iUserPLUCode);// Array of objects function calls
paPurchase[iUserItemCount].setdInventory(dUserAmount);
paPurchase[iUserItemCount].setdPrice(paInventory[iProductIndex].getdPrice());
paInventory[iProductIndex].setdInventory( paInventory[iProductIndex].getdInventory() - dUserAmount );
iUserItemCount++;
cout <<"Are you done purchasing items? Enter 1 for yes and 0 for no.\n";
cin >> bQuit;
//NOTE: Put Amount * quantity for subtotal
//NOTE: Put code to update subtotal (total += subtotal)
// NOTE: Need to create the output txt file!
}while(!bQuit);
return 0;
}

Answer 1

iUserItemCount is never initialised. You're invoking undefined behaviour when you use it as an index.

Answer 2

Because you work with statically allocated arrays you probably stumbled upon writing after the end of the array.
You state that the file has exactly 21 entries but what happens with the eof condition? If you read the last entry, the stream still doesn't have the eof bit set. This only happens when you try to read and there is nothing.
After the 21st entry, the loop still continues because the eof bit is not set. It reads garbage information and tries to store it into paInventory[21], but the array was only 21 in size.
//after last read x=21 and eof not set
while (!InputInventory.eof () )
{
//first read causes eof to be set
InputInventory >> iTempPluCode >> sTempDescription >> dTempPrice >> iTempType >> dTempInventory;
//Accessing paInventory[21] here which causes your error
paInventory[x].setiPluCode(iTempPluCode);
//...//
}