Thread: Random access files

Hi..this is my coding. Its compiled successfully. But i could not get my result. I don't know whether the data stored in the file successfully or not. Please Help me.

Code:

#include <iostream>
#include <fstream>
#include <cstring>
using namespace std;
struct status 
{
    char name[80];
    double balance;
    unsigned long account_num;
};


class FileHandler
{
public:
    FileHandler(const string&);
    ~FileHandler();
    
    int getRecords(struct status *);
    int putRecords(struct status *);
    int ReadRecord(int ,struct status *);
    int WriteRecord(int ,struct status *);
    

private:
    string fileName;
    fstream fPointer; // ref
};
FileHandler :: FileHandler(const string& fname)
{
    fPointer.open(fname.c_str(), ios::out | ios::binary);
}
int FileHandler :: WriteRecord(int RecNum,struct status *acc)
{
    if( fPointer.seekp(RecNum*sizeof(struct status), ios::beg) == 0 )
              if ( fPointer.write((char *) &acc, sizeof(struct status) ))
                return 1;
        return 0;
}
int FileHandler :: ReadRecord(int RecNum,struct status *acc)
{
    if( fPointer.seekg(RecNum*sizeof(struct status), ios::beg) == 0 )
              if ( fPointer.read((char *) &acc, sizeof(struct status) ))
                return 1;
        return 0;
}
FileHandler :: ~FileHandler()
{
    fPointer.close();
}
int FileHandler :: getRecords(struct status *acc)
{
    strcpy(acc->name, "Heartly");
    acc->balance = 1000;
    acc->account_num = 3;
    return 0;
}
int FileHandler :: putRecords(struct status *acc)
{
    cout << acc->name << endl;
    cout << "Account # " << acc->account_num;
    cout.precision(2);
    cout.setf(ios::fixed);
    cout << endl << "Balance: $" << acc->balance<<endl;
    return 0;
}
int main()
{
    FileHandler fp("abc.cli");
    struct status acc;
    fp.getRecords(&acc);
    fp.WriteRecord(0,&acc);
    strcpy(acc.name, "");
    acc.balance = 0;
    acc.account_num = 0;
    fp.ReadRecord(0,&acc);
    fp.putRecords(&acc);
    
    
}

RESULT IS

heartly@client6:~/cppprograms$ ./a.out

Account # 0
Balance: $0.00

Originally Posted by Salem

> if ( fPointer.write((char *) &acc, sizeof(struct status) ))
Remove the &

I removed. But still The result is not correct.

Code:

fPointer.open(fname.c_str(), ios::out | ios::binary);
fPointer.read((char *) &acc, sizeof(struct status) )

O_o

Soma

Originally Posted by phantomotap

Code:

fPointer.open(fname.c_str(), ios::out | ios::binary);
fPointer.read((char *) &acc, sizeof(struct status) )

O_o

Soma

What you are telling??? sorry. i could not get u

Actually, I was referring to the fact that the file hasn't been opened for writing.

Soma

^_^;

Soma -> asleep at the wheel

Originally Posted by Salem

It means do both of them!

if ( fPointer.write((char *) &acc, sizeof(struct status) ))
to
if ( fPointer.write((char *) acc, sizeof(struct status) ))

if ( fPointer.read((char *) &acc, sizeof(struct status) ))
to
if ( fPointer.read((char *) acc, sizeof(struct status) ))

If that doesn't work, post your latest code.

This is my new code :

Code:

#include <iostream>
#include <fstream>
#include <cstring>
using namespace std;
struct status 
{
    char name[80];
    double balance;
    unsigned long account_num;
};


class FileHandler
{
public:
    FileHandler(const string&);
    ~FileHandler();
    
    int getRecords(struct status &);
    int putRecords(struct status &)const;
    int ReadRecord(int ,struct status *);
    int WriteRecord(int ,struct status *);
    

private:
    string fileName;
    fstream fPointer; // ref
};
FileHandler :: FileHandler(const string& fname)
{
    fPointer.open(fname.c_str(), ios::out | ios::in | ios::binary);
}
int FileHandler :: WriteRecord(int RecNum,struct status *acc)
{
    if( fPointer.seekp(RecNum*sizeof(struct status), ios::beg) == 0 )
              if ( fPointer.write((char *) acc, sizeof(struct status) ))
                return 1;
        return 0;
}
int FileHandler :: ReadRecord(int RecNum,struct status *acc)
{
    if( fPointer.seekg(RecNum*sizeof(struct status), ios::beg) == 0 )
              if ( fPointer.read((char *) acc, sizeof(struct status) ))
                return 1;
        return 0;
}
FileHandler :: ~FileHandler()
{
    fPointer.close();
}
int FileHandler :: getRecords(struct status &acc)
{
    strcpy(acc.name, "INFANT");
    acc.balance = 1000;
    acc.account_num = 3;
    return 0;
}
int FileHandler :: putRecords(struct status &acc)const
{
    cout << acc.name << endl;
    cout << "Account # " << acc.account_num;
    cout.precision(2);
    cout.setf(ios::fixed);
    cout << endl << "Balance: $" << acc.balance<<endl;
    return 0;
}
int main()
{
    FileHandler fp("abc.cli");
    struct status acc;
    fp.getRecords(acc);
    fp.WriteRecord(0,&acc);
    strcpy(acc.name, "");
    acc.balance = 0;
    acc.account_num = 0;
    fp.ReadRecord(0,&acc);
    fp.putRecords(acc);
    
    
}

Originally Posted by Salem

Well I see no file created when I run that code.

I also see an error message when I add this after open

Code:

    if ( !fPointer ) {
      cout << "Failed to open" << endl;
    }

Then what is the problem here?? should i declare the fPointer as reference???

Originally Posted by Salem

Well I see no file created when I run that code.

I also see an error message when I add this after open

Code:

    if ( !fPointer ) {
      cout << "Failed to open" << endl;
    }

if i open like this, the file is created successfully.

Code:

fPointer.open(fname.c_str(), ios::out | ios::binary);
    if ( !fPointer ) 
    {
          cout << "Failed to open" << endl;
    }

But i need to open as write and read mode.