Sorting data in a binary file

[trojsi]

hi,
in a game menu for hangman game, I am trying to sort entries in a binary after I delete a user profile to remove the whitespace. My technique was to copy all the data after the deleted user profile into a string and then write it again to the file shifting back by 1 data structure. I am sure about the cursor positions because I am displaying them to check. I am writing the string back but unfortunately when checking the size of string, it only holds 32 bytes of data while a single struct has 48bytes. When I read that struct back I read garbage. below is my code:

void DeleteUser()

{

PlayerInfo sPlayer = {0};
	
// show initial contents
fstream finout; // read and write streams
finout.open(pszFileName, ios_base::in | ios_base::out | ios_base::binary);
	

int ct = 0;
int sCount =0;
	
if (finout.is_open())
	{
	finout.seekg(0); // go to beginning
	cout << "Here are the current contents of " << pszFileName << endl << endl ;
	
		while (finout.read((char *) &sPlayer, sizeof(sPlayer)))
		{
			
		cout << ct++ << ": " << sPlayer.szName << " "
		<< sPlayer.nAge << " " << sPlayer.nScore << " "
		<< sPlayer.szLastword << " "<< endl;
		}

	
		if (finout.eof())
			finout.clear(); // clear eof flag

		else
		{
			cerr << "Error in reading “ << file << “.\n";
			exit(EXIT_FAILURE);
		}
        }
	
		else
	{
		cerr << pszFileName << "could not be opened -- bye.\n";
		exit(EXIT_FAILURE);
	}

	cout << "Please Select a User Profile." << endl << endl;

	// change a record
	cout << "Enter the User Profile you wish to Delete: ";
	
	cin >> rec;
	eatline(); // get rid of newline

	if (rec < 0 || rec >= ct)
	{

		cerr <<"Invalid User number -- bye\n";
		exit(EXIT_FAILURE);
	}

	streampos place = rec * sizeof(sPlayer); // convert to streampos type
	finout.seekg(place); // random access

	
	if (finout.fail())
	{
		cerr << "Error on attempted seek\n";
		exit(EXIT_FAILURE);
	}

	finout.read((char *) &sPlayer, sizeof(sPlayer));
	
	cout << "Your selection:\n";
	cout << rec << ": " << sPlayer.szName << " "
	<< sPlayer.nAge << " " << sPlayer.nScore << " "
	<< sPlayer.szLastword << " "<< endl;
	 
	
	if (finout.eof())
	finout.clear(); // clear eof flag

	//PlayerInfo dPlayer = {0};

	//finout.seekp(place); // go back
	//finout.write((char *) &dPlayer, sizeof dPlayer) << flush;
	//eatline(); // get rid of newline

	//finout.seekp(place); // go back


	cout << finout.tellg() << endl;
	system("pause");
	int x=0;
	string buff;
	char tempChar;

	while ( !finout.eof() ) 
	{
	
         finout.get(tempChar);
         buff += tempChar;
	 x++;
         }
    
        finout.clear(); // clear eof flag
	
	cout << "eof reached" << endl;
	cout << "current pos " << finout.tellg() << endl;
	cout << buff << endl;

	//finout.seekg(48, ios::beg);
	finout.seekp(place); // go back
	
	cout << "current pos " << finout.tellg() << endl;
	
	cout << "size of buff: " << (sizeof(buff)) << endl;
	cout << "size of x :" << x << endl;
	
	system("pause");

	
	if (finout.is_open() == true)
	{
		
		//oFile.write((char*) &Infowrite, sizeof(Infowrite));
		finout.write((char *)&buff, x-1) << flush;
	}
	else
	{
		cout << "Failed to open file " << pszFileName << endl;
	}
	

	if (finout.fail())

	{
		cerr << "Error on attempted write" << endl;
		exit(EXIT_FAILURE);
	}

	cout << "oki" << endl;
	system("pause");
	
	SelectUser();
}

[Texan40]

Trying to delete user data in-place from a file seems like a bad design. Read all the user data, delete/add what you want, then dump it all back to file at once.

[trojsi]

Can you specify your method in more step by step pls and what to use to read all data from file (string, char array etc.) and if it is possible to remove just one struct from the whole bunch of data if I put all of it in a string?