include <stdio.h>void main(){ float r;printf("请输入圆的半径: ");scanf("%f",&r);printf("圆的周长是: %f\n",(2*3.14*r));//求出圆周长 printf("圆的面积是: %f\n",(3.14*r*r));//求出圆面积 }
include <stdio.h>void main(){ float r;printf("请输入圆的半径: ");scanf("%f",&r);printf("圆的周长是: %f\n",(2*3.14*r));//求出圆周长 printf("圆的面积是: %f\n",(3.14*r*r));//求出圆面积 }
include<stdio.h> define PI 3.14 void main(){ float r,l,area;printf("please input r:\n");scanf("%f", &r);if(r>=0){ area=PI*r*2;l=2*PI*r;printf("the area is %.2f\n", area);printf("the l is %.2f\n", l);} else printf("Input error!\n");return 0;...