#include <iostream>
#include <fstream>
#include <string>

using namespace std;

bool isnum(string s)
{ const int len = s.length();
  int i = 0;
  while (i < len)
  { char c = s[i];
    if (c < '0' || c > '9')
      return false;
    i = i + 1; }
  return true; }

int numericval(string s)
{ const int len = s.length();
  int total = 0;
  for (int i = 0; i < len; i += 1)
  { char c = s[i];
    int v = (int)c - (int)'0';
    total = total * 10 + v; }
  return total; }

struct element
{ int atno;
  string symbol, name;
  double atwt; };

void print(element e)
{ cout << e.atno << ", ";
  cout << e.symbol << ", ";
  cout << e.name << ", ";
  cout << e.atwt << "\n"; }

struct pertab // short for periodic table
{ static const int arrsize = 120;
  element table[arrsize];
  int numels; };

void empty(pertab & PT)
{ PT.numels = 0; }

void read_elements(pertab & PT)
{ ifstream fin;
  fin.open("/home/www/class/een118/a3010b.txt");
  if (fin.fail())
  { cout << "Can't read file\n";
    exit(1); }

  PT.table[0].atno = 0;
  PT.table[0].symbol = "?";
  PT.table[0].name = "ERROR!!!!!!!!!";
  PT.table[0].atwt = -999999999999999.9;

  int atno = 0;
  while (atno < PT.arrsize - 1)
  {
    string symbol, name;
    double atwt;
    fin >> symbol >> name >> atwt;
    if (fin.fail())
      break;

    atno = atno + 1;

    PT.table[atno].atno = atno;
    PT.table[atno].symbol = symbol;
    PT.table[atno].name = name;
    PT.table[atno].atwt = atwt;
  }
  cout << atno << " Elements successfully read\n";
  fin.close();
  PT.numels = atno; 
}

element find_elem(string sym, const pertab & PT)
{ int i = 1;
  while (i <= PT.numels)
  { if (sym == PT.table[i].symbol)
      return PT.table[i];
    i = i + 1; }
  return PT.table[0]; }      // 0 means not found

int main()
{ pertab PT;
  empty(PT);
  read_elements(PT);
  
  double molwt = 0.0;
  cout << "Enter a formula: ";
  bool ok = true;
  double lastatwt = 0.0;

  while (true)
  { string s;
    cin >> s;

    if (s == ".")
      break;

    if (isnum(s))
    { int n = numericval(s);
      molwt += (n - 1) * lastatwt;
      cout << "Revised " << lastatwt << " to " << n * lastatwt << "\n";
      continue; }

    element e = find_elem(s, PT);
    if (e.atno == 0)
    { cout << s << ": No such element\n";
      ok = false;
      continue; }

    lastatwt = e.atwt;
    print(e);
    molwt = molwt + e.atwt; }

  if (ok)
    cout << "Molecular weight = " << molwt << "\n";
  else
    cout << "There was an error in the input\n";
}