D. 实验1_4_求圆的周长与面积

#include<stdio.h>
#define PI 3.14159265
int main(void)
{
	double r,s,c;
	scanf("%lf",&r);
	s=PI*r*r;
	c=PI*2*r;
	printf("The perimeter is %.4lf,the area is %.4lf.\n",c,s);
	return 0;
}