Question

C语言编写一程序，从键盘输入圆半径r，求圆周长l和圆面积s。输出时要有文字说明，

Answer 1

#include"math.h"
#include"stdio.h"
#define pai=3.1415926

void main()
{ float r,l,s;
printf("input r:\n");
scanf("%f",&r);
l=2*r*pai;
s=pai*r^2;
printf("周长=%.2f\n,面积=%.2f\n",l,s);
}

Answer 2

借花献佛，刚回答别人的问题

#include"math.h"
#include"stdio.h"

void main()
{ float r,l,s;
printf("input r:\n");
scanf("%f",&r);
l=2*r*3.1415926;
s=r*r*3.1415926;
printf("周长=%.2f\n,面积=%.2f\n",l,s);
}

Answer 3

#include <stdio.h>
#define PI 3.1415926

int main()
{
double c, r, area;
printf("半径=");
scanf("%lf", &r);
c = 2 * PI * r;
area = PI * r * r;
printf("周长=%f，面积=%f\n", c, area);
return 0;
}

Answer 4

#include<stdio.h>
int main() {
const float PI = 3.14;
long double r,l,s;
printf("请输入圆的半径r:");
scanf("%lf", &r);
l= 2 * PI*r;
s = PI*r*r;
printf("圆的周长l是%lf,圆面积s是%lf.\n",l,s);
return 0;
}

Answer 5

#include <stdio.h>
#define Pi 3.1415926
int main(void){
float r,l,s;
printf("r=");
scanf("%f", &r);
l=2*Pi*r;
s=Pi*r*r;
printf("面积：%f, 周长：%f¥n", s, l);
return 0;
}