#include <iostream.h>
#include <fstream.h>
#include <iomanip.h>
#include <limits.h>
#include <string.h>
#include <ctype.h>
#include <conio.h>

// program limitations
const int max_line_length = 100,
          max_words = 200,
          max_word_length = 40,
          max_filename_length = 60;


void pause (void) {

  cout << "Hit any key to continue...\n";
  getch ();

}


bool get_next_word (const char string[], int &start, char word[]) {

  int i;

  // advance until we hit a letter, a number, or the terminator
  while (!isalnum(string[start]) && (string[start] != '\0')) {
    start++;
  }

  if (string[start] == '\0') {
    return false;
  }

  // copy until we get something that isn't alphanumeric
  i = 0;
  do {
    word[i++] = string[start++];
  } while (isalnum(string[start]));
  word[i] = '\0'; // terminate word

  return true;

}


void update_word_list (char word[], char word_list[][max_word_length + 1],
                       int counters[], int &word_count) {

  int i;

  // see if the word is already on our list
  for (i = 0; i < word_count; i++) {
    if (stricmp(word_list[i], word) == 0) {
      // word exist on list - all we need do is update the count
      counters[i]++; return;
    }
  }

  if (word_count == max_words) {
    // no more room - report the problem and ignore the word
    cout << "Unable to add <" << word << "> to the word list (list full).\n";
    return;
  }

  strcpy (word_list[word_count], word);
  counters[word_count++] = 1; // one occurrance so far

}


void sort_word_list (char word_list[][max_word_length + 1], int counters[],
                     int word_count) {

  char word_temp[max_word_length + 1];
  int i, j, count_temp;

  for (i = 0; i < word_count - 1; i++) {
    for (j = i + 1; j < word_count; j++) {
      if (stricmp(word_list[i], word_list[j]) > 0) {
        strcpy (word_temp, word_list[i]);
        strcpy (word_list[i], word_list[j]);
        strcpy (word_list[j], word_temp);
        count_temp = counters[i];
        counters[i] = counters[j];
        counters[j] = count_temp;
      }
    }
  }

}


void main (void) {

  char line [max_line_length + 1]; // allow for terminator
  ifstream fin;
  ofstream fout;
  char filename[max_filename_length + 1], word[max_word_length + 1];
  int counters[max_words],
      word_count = 0, // number of different words
      total_words = 0, // total number of words
      start, i;
  char word_list[max_words][max_word_length + 1];

  cout << "Please enter the name of the input file: ";
  cin >> setw(max_filename_length + 1) >> filename;
  fin.open (filename);
  if (fin.fail()) {
    cout << "Unable to open file " << filename << ".\n";
    pause ();
    return;
  }

  cout << "PLease enter the name of the output file: ";
  cin >> setw(max_filename_length + 1) >> filename;
  fout.open (filename);

  for (;;) {

    fin.getline (line, max_line_length + 1);

    if (fin.fail()) { // read didn't work for some reason

      if (!fin.eof()) { // some kind of error occurred
        // warn user that an problem occurred
        cout << "An error occuring in reading the input file.\n";
        // we could abort here, but it makes to more sense to
        // continue and output what we've got (i.e. to treat the
        // error as a kind of end of file condition)
      }

      break;

    }

    // process all of the words in the line we've just read
    start = 0;
    for (;;) {

      if (!get_next_word (line, start, word)) {
        break; // no more words to process
      }

      // start has now been updated (by the function) so that it's
      // all ready for the extraction of the next word

      update_word_list (word, word_list, counters, word_count);

      total_words++;

    }

  }

  sort_word_list (word_list, counters, word_count);

  // write results to the output file
  fout << "The file processed contains " << total_words << " total words.\n"
       << "There are " << word_count << " different words.\n"; 
  for (i = 0; i < word_count; i++) {
    fout << setw(3) << counters[i] << " : " << word_list[i] << endl;
  }

  cout << "Results successfully written to file.\n";
  pause ();

}