Sorting and searching with user-defined records

// Program to demonstrate sorting and searching of personnel records,
// showing how to define a function object that tells how to compare two
// such records.

#include <mstring.h>
#include <vector.h>
#include <algo.h>

struct person {
  string first_name;
  string last_name;
  int number;
};

void output(const person& record) 
{
     cout << record.first_name << " " << record.last_name 
          << ", Record No. " << record.number << "\n";
}

int rec_no = 1;   // shouldn't really be a global variable

void read_names(vector<person>& roster)
{
  person person1;
  while (true) {
     cin >> person1.first_name;
     if (person1.first_name == string("---")) 
         break;
     cin >> person1.last_name;
     person1.number = rec_no++;
     roster.push_back(person1);  // put person1 at end of roster
  }
}

// Following is a function object type, 
// defines how to compare persons (for sorting/searching)
struct NameCompare {  
  bool operator()(const person& a, const person& b) {
      return a.last_name < b.last_name;  // based on last names only
  }
};

NameCompare nameComp;  /* declare a comparison function object, to
                          pass to sort and search algorithms */

int main() 
{
  vector<person> roster;

  read_names(roster);

  sort(roster.begin(), roster.end(), nameComp);

  cout << "Current persons, listed alphabetically by last name:\n\n";

  for (vector<person>::iterator i = roster.begin();
       i != roster.end(); ++i) 
      output(*i);
  cout << "\n\n";

  person search_record;

  while (true) {

     cin >> search_record.last_name;

     if (search_record.last_name == string("---")) 
         break;

     cout << "Searching for a person named " 
          << search_record.last_name << "...\n";

     i = lower_bound(roster.begin(), roster.end(), 
                     search_record, nameComp);

     if ((*i).last_name == search_record.last_name) {
        cout << "Found ";
        output(*i);
        cout << "\n";
     } else
        cout << "Sorry, there's no record of a person named "
             << search_record.last_name << "\n\n";
  }
  return 0;
}