60   char *endp;

    60   bool decimalPtSeen = false;

    61   double unused = strtod(s.c_str(), &endp); // declared with warn_unused_result

    61   bool exponentSeen = false;

    62   unused = unused; // quiet compiler

    62   char last = '\0';

    63   return endp == s.c_str() + s.size();

    63 

    64   for (std::string::const_iterator it = s.begin (); it != s.end (); it++)

    65     {

    66       if ((*it == '.') && (decimalPtSeen))

    67         return false;

    68       else if (*it == '.')

    69         decimalPtSeen = true;

    70       else if ((*it == 'e') && exponentSeen)

    71         return false;

    72       else if (*it == 'e')

    73         {

    74           exponentSeen = true;

    75           decimalPtSeen = false;

    76         }

    77       else if (*it == '-' && it != s.begin () && last != 'e')

    78         return false;

    79 

    80       last = *it;

    81     }

    82   return true;