C++ presicion

gistfile1.cpp

#include <iostream>
#include <iomanip>
#include <sstream>

using namespace std;

int main() {

  std::string str = "2.492089450701739E62";
  double d;
  stringstream ss;
  ss << str;
  ss >> d;
  std::cout << std::setprecision(15) << d << std::endl;
  std::cout << std::setprecision(15) << 1.0 / 3 << std::endl;
  return 0;
}