那用ｃ语言编写一个程序从键盘输入圆的半径计算该圆的周长面积。并输出

Answer 1

#include <stdio.h>
void main()
{
float r; //半径
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
}

Answer 2

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define PI 3.14159
int main()
{
float r,s,c;
scanf("%f",&r);
s=PI*r*r;
c=2*PI*r;
printf("%g\n",c);
printf("%g\n",s);
return 0;
}

Answer 3

#include <stdio.h>
#include <math.h>

int main()
{
double r,s,a;
double pi=asin(1.0)*2.0;
printf("input r:\n");
scanf("%lf",&r);
s = 2.0*r*pi;
a = pi * r *r;
printf("s=%lf area=%lf\n",s,a);

return 0;
}

Answer 4

#define PAI 3.14
int main()
{
double r;
printf("please input r:\n");
scanf("%f",r);
printf("length of the circle = %f\n",2 * PAI *r);
printf("area of the circle = %f\n",PAI * r * r);
return 1;
}