#include <iostream>
#include <iomanip>
#include <fstream>
#include <string>
#include <cstring>

using namespace std;

/*
     f.open(string name);
     f.open(string name, ios::in | ios::out | ios::binary | ios::trunc | ios::app | ios::ate);
     f.write(char * pointer, int numbytes);
     f.read(char * pointer, int numbytes);
     int bytesread = f.gcount();
     int f.tellg();    // reading position
     int f.tellp();    // writing position
     f.seekg(int relative_position, ios::beg or ios::end or ios::cur);
     f.seekp(int relative_position, ios::beg or ios::end or ios::cur);
*/

int main(int argc, char * argv[])
{ char wanted[60];
  strcpy(wanted, argv[1]);
  int len = strlen(wanted);
  for (int i = len; i < 48; i += 1)
    wanted[i] = ' ';
  wanted[48] = '\0';
  cout << "search for \'" << wanted << "\'\n";
  
  const string fname = "/home/www/class/een318/named-places.txt";
  ifstream fi(fname);
  if (fi.fail())
  { cerr << "Can't read \"" << fname << "\"\n";
    exit(1); }

  fi.seekg(0, ios::end);
  int filesize = fi.tellg();
  fi.seekg(0, ios::beg);

  char line[120];
  int nrec = filesize / 115;               // [115] is the position of the '\n' character
  int first = 0, last = nrec - 1;
  while (first <= last)
  { int mid = (first + last) / 2;
    fi.seekg(mid * 115, ios::beg);
    fi.read(line, 115);
    line[115] = '\0';
    cout << "seeing " << mid << ": '" << line << "'\n";
    char c = line[58];
    line[58] = '\0';                       // line is now a C string that stops at position 58, where population begins
    int r = strcmp(line + 10, wanted);     // line + 10 skips the numeric code and state abbreviation
    if (r == 0)
    { line[58] = c;                        // set line back to be the whole record not ending until [115]
      cout << "record " << mid << ": '" << line << "'\n";
      break; }
    if (r > 0)
      last = mid - 1;
    else
      first = mid + 1; }
  fi.close(); }