printf("直径为:%0.02f\n圆的面积为:%0.03f\n周长为:%0.02f",2*r,area,perimeter);return 0;}
return(_area);}int main(){ float r,a,b; scanf("%f",&r); a=perimeter(r); b=area(r); printf("perimer=%g,area=%g\n",a,b); system("
include<stdio.h>#include<math.h>int main(){float s;float r;float l;scanf("%f",&s);r=sqrt(s/3.1415926);l=2*r*3.1415926;printf("周长：%f\n半径：%f\n",l,r);return 0;}