file buffer duplication using string streams

filebuff.cpp

#include <vector>
#include <fstream>
#include <sstream>
#include <iostream>

int main(int argc, char* argv[]) {
  if(argc != 3) {
    std::cerr << "Usage: " << argv[0] << " <filename> <num_iters>" << std::endl;
    return 0;
  }
  int iters = atoi(argv[2]);
  std::string filename(argv[1]);
  std::ifstream istr(filename);

  if (!istr) {
    std::cerr << "ERROR: cannot open file " << filename << std::endl;
    exit(1);
  }
  //get the length of the file
  istr.seekg(0,std::ios::end);
  std:: streampos length = istr.tellg();
  istr.seekg(0,std::ios::beg);

  std::vector<char> buffer(length);
  //read the file into the buffer
  istr.read(&buffer[0], length);
 //load the file buffer into a string stream
 std::stringstream root;
 root.rdbuf()->pubsetbuf(&buffer[0],length); 

  //doing something with a copy of filebuffer
  while (iters > 0) {
    std::cout << iters << std::endl;
    iters--;
    // create a copy string
    std::stringstream partstr(root.str());
    //do work with string stream
  }
  return 0;
}