Floating point c (mks)

fpc.cpp

#include <iostream>
#include <iomanip>
#include <limits>

using namespace std;

#define PREC std::setprecision(std::numeric_limits<long double>::digits10 + 1)

int main() {
  float c_float;
  double c_dble;

  cout << "Single precision" << endl;

  c_float = 299792458;
  cout << PREC << c_float << endl;

  c_float = 299792458.0f;
  cout << PREC << c_float << endl;

  c_float = 299792458.0;
  cout << PREC << c_float << endl;

  cout << PREC << "Double precision" << endl;

  c_dble = 299792458;
  cout << PREC << c_dble << endl;

  c_dble = 299792458.0f;
  cout << PREC << c_dble << endl;

  c_dble = 299792458.0;
  cout << PREC << c_dble << endl;

  return 0;
}

fpc.f90

program test
  implicit none

  real(8) :: c_real
  real    :: c_flt

  write(*,*) "Floating point"

  c_flt = 299792458
  write(*,*) c_flt

  c_flt = 299792458.0
  write(*,*) c_flt

  c_flt = 299792458d0
  write(*,*) c_flt

  write(*,*) "Double precision"

  c_real = 299792458
  write(*,*) c_real

  c_real = 299792458.0
  write(*,*) c_real

  c_real = 299792458d0
  write(*,*) c_real
end program test