C 程序 计算圆的面积和周长

面积 = 3.14 * 半径 * 半径
周长 = 2 * 3.14 * 半径

#include <stdio.h>
int main()
{
   int circle_radius;
   float PI_VALUE=3.14, circle_area, circle_circumf;

   //Ask user to enter the radius of circle
   printf("\nEnter radius of circle: ");
   //Storing the user input into variable circle_radius
   scanf("%d",&circle_radius);

   //Calculate and display Area
   circle_area = PI_VALUE * circle_radius * circle_radius;
   printf("\nArea of circle is: %f",circle_area);

   //Caluclate and display Circumference
   circle_circumf = 2 * PI_VALUE * circle_radius;
   printf("\nCircumference of circle is: %f",circle_circumf);

   return(0);
}

Enter radius of circle: 2
Area of circle is: 12.560000
Circumference of circle is: 12.560000