用c语言编写函数，求圆的周长和面积，用函数。急求。。

Question

如题所述

Answer 1

#include<stdio.h>
#define PI 3.1415926
double area(double r)
{
return PI * r * r;
}

double perimeter(double r)
{
return 2 * PI * r;
}

int main()
{
printf("请输入半径的值:\n");
double r;
scanf("%lf",&r);
printf("周长为%lf\n",perimeter(r));
printf("面积为%lf\n",area(r));
return 0;
}

Answer 2

main()
{
float r;
float zl(float r);
float mj(float r);
printf("请输入圆的半径：\n",r);
scanf("%f",&r);
printf("圆的周长为：%f",zl(r));
printf("圆的面积为：%f",mj(r));
}
float zl(float r)
{
float l;
l=2*r*3.14;
return l;
}
float mj(float r)
{
float s;
s=r*r*3.14;
return s;
}

Answer 3

#include <stdio.h>
void main()
{
float r,pi=3.14,c,s;
printf("input r=");
scanf("%f",&r);
c=2*pi*r;
s=pi*r*r;
printf("周长c=%lf\n",c);
printf("面积s=%lf\n",s);
}

Answer 4

#include<stdio.h>
#define PI 3.141592
float Z(float r)
{return 2*PI*r;}
float M(float r)
{return PI*r*r;}
void main()
{float r,s,z;
printf("输入半径r=");
scanf("%f",&r);
s=M(r);
z=Z(r);
printf("周长为%f\n面积为%f\n",z,m);
}