Read Binary File Records Show Only Junk Values

[Science001]

I tried to write a Program to store Info of Items in a Binary File. But except the 1st record, all other Records read thro' ShowFile() show only junk value. I have been trying to find the problem, but my code seems to be error-free to me. So, fellow Programmers help your newbie, find his Mistakes! (Note: I used Turbo C++ for compiling). Here is the code:

#include <fstream.h>
#include <stdio.h>
#include <conio.h>
#include <process.h>

class store
{
	int ino, stock;
	char iname[100];
	float price;
	char chline;

	public:
	void NewItem()
	{
		cout<<"\n\nNew Item Registration:\n\nItem No.: "; cin>>ino;
		cout<<"\nItem Name: "; gets(iname);
		cout<<"\nPrice: "; cin>>price;
		cout<<"\nQuantity: "; cin>>stock;
		cout<<"\nRegistered!";
	}

	int returnIno()
	{
		return ino;
	}

	void Details()
	{
		cout<<"\n\nItem No.: "<<ino<<"\nItem Name: "<<iname<<"\nPrice: "<<price<<"\nStock: "<<stock;
	}
};


void NewFile()
{
    store s;
    ofstream f1;
    f1.open("stores.dat",ios::binary);
    char ch;
	cout<<"\n\nFresh file \"stores.dat\" created! Any previous content of any file of the SAME NAME is deleted!";
    do
    {
		s.NewItem();
		f1.write((char*)&s, sizeof(s));
		f1<<endl;
		cout<<"Do you want to Add more Items > (y/n):\t";
		cin>>ch;
    }while (ch=='y');
    cout<<"All Entries have been Stored in the File successfully!";
	f1.close();
}

void ShowFile()
{
	clrscr();
	store s;
	ifstream f1;
	f1.open("stores.dat", ios::binary);
	cout<<"\n\nShowing Contents of the File";
	f1.seekg(0);
	while(f1.read((char*)&s,sizeof(s)))
	{
			s.Details();
	}
	f1.close();
}

int main()
{
    clrscr();
	int choice;
	cin>>choice;
	if(choice==1) NewFile();
	else if(choice==2) ShowFile();
	else exit(0);
	getch();
}

[Chervil]

Line 46

        f1<<endl;

looks like a problem.
I suggest that line is deleted, it isn't matched by any corresponding file input in the ShowFile() function, which would explain why things get out of sync after the first record.

[Thomas1965]

I would read and write it like this:

void SaveToStream (ofstream& os)
  {
    os.write ((const char *)&ino, sizeof (ino));
    os.write ((const char *)&stock, sizeof (stock));
    os.write ((const char *)iname, sizeof (iname));
    os.write ((const char *)&chline, sizeof (chline));
    os.write ((const char *)&price, sizeof (price));
  }
  void LoadFromStream (ifstream& is)
  {
    is.read ((char *)&ino, sizeof (ino));
    is.read ((char *)&stock, sizeof (stock));
    is.read ((char *)iname, sizeof (iname));
    is.read ((char *)&chline, sizeof (chline));
    is.read ((char *)&price, sizeof (price));
  }

Output:

New Item Registration:

Item No.: 1

Item Name: Hammer

Price: 10

Quantity: 10

Registered!

Item No.: 1
Item Name: Hammer
Price: 10
Stock: 10

Showing Contents of the File

Item No.: 1
Item Name: Hammer
Price: 10
Stock: 10

[Science001]

Thomas1965, Where did you insert those two functions of yours in the Code?

[Thomas1965]

Actually I created a seperate test project for it. In your program I would add them to the class store and call them in NewFile and ShowFile.

void ShowFile()
{
   clrscr();
   store s;
   ifstream f1;
   f1.open("stores.dat", ios::binary);
   cout<<"\n\nShowing Contents of the File";

	while(f1)
	{
           s.LoadFromStream(f1);
	   s.Details();
	}
	f1.close(); // not needed
}

void NewFile()
{
    store s;
    ofstream f1;
    f1.open("stores.dat",ios::binary);
    char ch;
	cout<<"\n\nFresh file \"stores.dat\" created! Any previous content of any file of the SAME NAME is deleted!";
    do
    {
		s.NewItem();
		s.SaveToStream(f1);
		cout<<"Do you want to Add more Items > (y/n):\t";
		cin>>ch;
    }while (ch=='y');
    cout<<"All Entries have been Stored in the File successfully!";
	f1.close(); // not needed
}

[Science001]

Oh Yeah! Thanks Thomas1965. The code is finally working!

But Only one Problem.
Using while(f1) reads the last file two times. And using while(s.LoadFromStream(f1)) also seems to be an error!
So, Is there another way to counter the problem!

[Thomas1965]

And using while(s.LoadFromStream(f1)) also seems to be an error!

Your idea was right - just modify LoadFromStream, then it should work.

ifstream& LoadFromStream (ifstream& is)
  {
    is.read ((char *)&ino, sizeof (ino));
    is.read ((char *)&stock, sizeof (stock));
    is.read ((char *)iname, sizeof (iname));
    is.read ((char *)&chline, sizeof (chline));
    is.read ((char *)&price, sizeof (price));

    return is;
  }

BTW. Your input need some fixing as well:

void NewItem ()
  {
    cout << "\n\nNew Item Registration:\n\nItem No.: "; 
    cin >> ino;
    cin.ignore (255, '\n');
    cout << "\nItem Name: "; 
    gets (iname);
    cout << "\nPrice: "; 
    cin >> price;
    cin.ignore (255, '\n');
    cout << "\nQuantity: "; 
    cin >> stock;
    cin.ignore (255, '\n');
    cout << "\nRegistered!";
  }

[Science001]

Thank you, Thomas1965. The code is now Perfect!

For the NewItem(), I had problem only with reading the string. And cin>>ws; helped it out.

So, is it okay or do you want me to fix my Code as you've posted. Also, a small explanation for such a fix, would help me increase my skills too!

And anyway, THANK YOU so much for such great support!

[Thomas1965]

If it works then there is nothing to fix.
A common problem with cin is that '\n' remains in the input buffer and the next input is skipped.
Normally you use cin.ignore (255, '\n'); to remove the '\n' from the input buffer.

[Science001]

Oh! Never knew that! Thanks for sharing a piece of knowledge... :)
Once again, THANK YOU!!!!!!

[Science001]

As a continuation, I tried to Insert records to my file. IDK why, the code doesn't seem to be working :(

I posted it as a seperate Query. Here is the link:
http://www.cplusplus.com/forum/general/194469/#msg935513