/*
   This just shows the parts of the progrm that relate to
   the nicestream, today's real topic
*/

struct nicestream      // intended to be nicer and more convenient for us than "cin >>"
{ string wholeline;
  int numtaken;
  int length;
  bool ended; };

char readchar(nicestream & ns)
{ char c;
  if (ns.numtaken >= ns.length)
    c = '\n';
  else
    c = ns.wholeline[ns.numtaken];
  ns.numtaken += 1;
  return c; }

char sneakchar(const nicestream & ns)
{ return ns.wholeline[ns.numtaken]; }

void unreadchar(nicestream & ns)
{ if (ns.numtaken > 0)
    ns.numtaken -= 1; }

void refill(nicestream & ns)
{ getline(cin, ns.wholeline);
  if (cin.fail())
  { ns.wholeline = "\n";
    ns.ended = true; }
  else
  { ns.wholeline += '\n';
    ns.ended = false; }
  ns.length = ns.wholeline.length();
  ns.numtaken = 0; }

bool ok(const nicestream & ns)
{ return ! ns.ended; }

/*
  This is the part of main that processes the molecular formula
*/

  nicestream nin;
  refill(nin);
  while (true)
  { char c = readchar(nin);

    if (c >= 'A' && c <= 'Z')
    { string symbol = "";
      symbol += c;
      c = sneakchar(nin);
      if (c >= 'a' && c <= 'z')
      { c = readchar(nin);
        symbol += c; }
      cout << "The symbol is '" << symbol << "'\n"; }

    else if (c == '\n')
      break;

    else if (c >= '0' && c <= '9')
    { int num = 0;
      while (c >= '0' && c <= '9')
      { num = num * 10 + c - '0';
        c = readchar(nin); }
      unreadchar(nin);
      cout << "number " << num << "\n"; }

    else
      cout << "Only dealing with symbols yet\n"; }

  cout << "I would say the molecular weight here\n";