Uploading Vector To File

[lifeofjdm]

I am now using Dev-C++ 4, and am trying to upload my vector elements using the infile as I did with VC4, but I do realize that they are not the same.

#include <fstream>
#include <vector>
#include <string>
#include <stdlib.h>

int main()
{
  // dcelare variables
  ifstream infile;
  std::vector <string> username;
  username.reserve(100);
  short index;

  // get usernames from file
  infile.open("user_db.dat", ios::in);
  index = username.size();
  do
  {
    index--;
    infile >> username[index];
  }
  while(index != 0);

  infile.close();
  system("PAUSE");
  return 0;
}

It compiles right, but I get an error when running it saying it has performed an illegal operation and closes. Any help?

JDM