Man, this stuff gets confusing!

//Obtain the size of the file without moving the file pointer
unsigned long fileSize(fstream file)
{
	unsigned long position = file.tellg();

	//Move pointer to end
	file.seekg(0, ios::end);

	//Record size in bytes
	unsigned long size = file.tellg();

	//Return file pointer to original location
	file.seekg(position, ios::beg);

	return size;
}

Any help is appreciated.

Also, is there a tutorial on advanced operations with binary files? I’m writing a file archive application and I need a little help with the C++ filestream objects.
I would like to weave files together byte by byte. I would also like to write variables, like the number and names of files in the archive, to the top of the file for easy reference.

Thank you for these tutorials. They have been a great resource for me.

#include<iostream>
#include <fstream>
using namespace std;

int main()
{
	int b[4]={1,1,5,1};
	int c[4]={0};
	fstream A("File.txt",ios::binary|ios::in|ios::out);
	if(!A)
	{
		return 1;
	}
	A.write((char *) (&b),sizeof(b));//(&b) must be (b) but ?????!!!!!
	A.seekg(0);
	A.read((char *) (c),sizeof(c));
	cout<<c[2];
	return 0;
}

#include
#include
using namespace std;

int main()
{
	int b[4]={1,1,5,1};
	int c[4]={0};
	fstream A("File.txt",ios::binary|ios::in|ios::out);

	if(!A)
	{
		return 1;
	}
	A.write((char *) (&b),sizeof(b));//(&b) must be (b) but ?????!!!!!
	A.seekg(0);
	A.read((char *) (c),sizeof(c));
	cout<<c[2];
	return 0;
}

I added :

#include <fstream>// ***  added for fstreams

using namespace std; //moved outside of main

//and finally opened in binary mode
fstream iofile("Sample.dat", ios::binary | ios::in | ios::out);
// **** the binary part is important otherwise the position is off

I added a short blurb about tellg() and tellp() to the tutorial and also changed the example to use iofile.seekg(iofile.tellg(), ios::beg);, though I do have some concerns about the performance ramificaitons of doing such a thing (not sure if it’s smart enough to convert that into a relative position, or whether it’s going back to the beginning of the file each time and then counting it out).

As for the seekg()/seekp() difference, as far as I can tell with fstream they appear to be identical.