#include <iostream>
#include <fstream>
#include <string>
#include <iomanip> // needed for setw()

using namespace std;

int main() 
{

  double a;

  a = 123.456;

  cout << a << endl;

  cout.setf(ios::scientific);  // Sets flag
  cout << a << endl;
  cout.unsetf(ios::scientific); // clears flag

  cout << a << endl;

  // Always use save/restore instead of set/clear
  long flagSettings = cout.flags(); // saves flag settings
  cout.setf(ios::scientific); 
  cout << a << endl;
  cout.flags(flagSettings); // restore flag settings

  cout << a << endl;


  
  return 0;
}