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

using namespace std;

struct element
{ string symbol, name;
  int at_no;
  double at_wt; };

void print(element e)
{ cout << e.at_no << ": " << e.symbol << ", "
       << e.name << ", at wt = " << e.at_wt << "\n"; }

const int max_num_els = 110;

element table[max_num_els];

int num_els = 0;

void read_table(ifstream & f)
{ while (num_els < max_num_els)
  { f >> table[num_els+1].symbol 
      >> table[num_els+1].name 
      >> table[num_els+1].at_wt; 
    table[num_els+1].at_no = num_els + 1;
    if (f.fail())
      return; 
    num_els += 1; } }

int find(string sy)
{ for (int i = 1; i <= num_els; i += 1)
    if (table[i].symbol == sy)
      return i;
  return 0; }

int convert(string s)
{ int sofar = 0;
  for (int i = 0; i < s.length(); i += 1)
    sofar = sofar * 10 + s[i] - '0';
  return sofar; }

bool is_number(string s)
{ for (int i = 0; i < s.length(); i += 1)
    if ( ! (s[i] >= '0' && s[i] <= '9'))
      return false;
  return true; }

double read_formula()
{ double total = 0.0, prev_wt = 0.0;
  while (true)
  { string sy;
    cin >> sy;
    if (sy == ".")
      return total;
    if (is_number(sy))
    { int N = convert(sy);
      total += (N - 1) * prev_wt;
      cout << "  correcting " << prev_wt << " to " << N * prev_wt << "\n"; }
    else
    { int epos = find(sy);
      if (epos < 1)
      { cout << "element " << sy << " not known\n";
        while (true)
        { cin >> sy;
          if (sy == ".")
            break; }
        return 0; }
      print(table[epos]);
      prev_wt = table[epos].at_wt; 
      total += prev_wt; } } }

int main()
{ ifstream file("table.txt");
  if (file.fail())
  { cout << "Can't read table file\n";
    exit(1); }
  read_table(file);
  file.close();
  cout << num_els << " elements read\n";
  // print(table[92]);
  // print(table[104]);   // left over from an earlier test
  // print(table[1]);
  // print(table[8]);
  while (true)
  { cout << "Enter formula: ";
    double mol_wt = read_formula();
    cout << "molecular weight = " << mol_wt << "\n"; } }