C++ :: Creating Variable Name For Binary File

I'm attempting to split a large binary file into smaller manageable files for analysis. I've written most of the software but I'm stuck in a couple of places.

1. The binary file is split by looking at a couple of bytes to determine when to create a new file or continue appending to the current new file. The question is when I need to create a new file, how can I dynamically sign it a name? My intention is to rename each subfile by: "original_name" + new section id + ".log".

2. The start of each section is determined by a specific pattern (6 bytes of FF's). I'm running into an issue where the pattern check is checking for 5 bytes instead of 6 because the for..loop doesn't increment for one instance.

I've attached the code I have so far.

#include <iostream>
#include <stdlib.h>
#include <stdio.h>
#include <string>
#include <sstream>
using namespace std;

int append_to_file(FILE *f,long sec_start, long sec_end)

[Code] ...