Simple Phone List 2

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

using namespace std;

struct person {
  string firstname;
  string lastname;
  string phonenumber;
  void clear() {
    firstname.clear();
    lastname.clear();
    phonenumber.clear();
  }
  size_t length() {
    return firstname.length() +
           lastname.length() +
           phonenumber.length();
  }
};

int main() {

  ifstream inputfile;
  vector<person> directory;

  inputfile.open("phonedata.txt");

  if (inputfile.is_open()) {

    person per;
    vector<person>::iterator it;
    int count = 0;

    while (!inputfile.eof()) {

      per.clear();

      inputfile >> per.firstname >> per.lastname >> per.phonenumber;

      if (per.length()) {
        it = directory.begin();
        directory.insert(it + count++, per);
      }
    }

    inputfile.close();

    for (int i=0; i < directory.size(); i++) {
      cout << directory[i].firstname << " "
          << directory[i].lastname << "\t"
          << directory[i].phonenumber << "\n";
    }
  }
  else {
    cout << "Failed to open input file.\n";
  }

  return 0;
}