double to hex string & hex string to double

Question

What I\'m trying to do is to convert a double to hex string and then back to double.

The following code does conversion double-to-hex string.

char *          


        

Answer 1

I am surprised to see nobody has come up with the standard solution, which is the %a format specifier in the ISO C99 Standard.

#include 
#include 
#include 

std::string double2hexastr(double d) {

  char buffer[25] = { 0 };

  ::snprintf(buffer, 25, "%A", d); // TODO Check for errors

  return buffer;
}

double hexastr2double(const std::string& s) {

  double d = 0.0;

  ::sscanf(s.c_str(), "%lA", &d); // TODO Check for errors

  return d;
}


int main() {

  std::cout << "0.1 in hexadecimal: " << double2hexastr(0.1) << std::endl;

  std::cout << "Reading back 0X1.999999999999AP-4, it is ";

  std::cout << hexastr2double("0X1.999999999999AP-4") << std::endl;

}