istringstream iss(string(argv[2]));
        double t;
          if( !( iss>>t) ) {
                  exit(1);
          }


z0pt.cpp: In function ‘int main(int, char**)’:
z0pt.cpp:572: error: invalid operands of types ‘std::istringstream ()(std::string*)’ and ‘double’ to binary ‘operator>>’