// find the area of a circle, given radius.
#include <iostream.h>
#include <iomanip.h>

 const double PI = 3.1415927;

void main() {




	double radius, area;
   
     radius = 3.1;
     area = 3.14*radius*radius;

	 // setiosflags to fixed
	 cout << setiosflags(ios::fixed | ios::showpoint);

	 // define precision to be 5 (i.e. 5 decimal places)
	 cout << setprecision(5);
	 cout << "area correct to 5 d.p " << area << endl;

	  // define precision to be 22 (i.e. 22 decimal places)
	 cout << setprecision(22);
	 cout << "area correct to 22 d.p " << area << endl;


	 //reset iosflags
	 cout << resetiosflags(ios::fixed | ios::showpoint);

	 //setiosflags to scientific
	 cout << setiosflags(ios::scientific | ios::showpoint);
	 cout << setprecision(5);
	 cout << "area correct to 5 d.p " << area << endl;


}