通过半径计算圆直径、周长和面积

/* caculate the circle */
/* Input: radius */
/* Output:caculate the diameter perimeter and area */
#include<stdio.h>
int main(){
    /* declaration */
    int int_radius;
    /* declaration */
    float float_Pi = 3.14159;
    /* prompt */
    printf("Please Enter the radius: ");
    /* prompt */
    scanf("%d", &int_radius);
    /* caculate the diameter */
    printf("The diameter is: %d\n", int_radius * 2);
    /* caculate the perimeter */
    printf("The perimeter is: %f\n", int_radius * 2 * float_Pi);
    /* caculate the area */
    printf("The area is: %f\n", int_radius * int_radius * float_Pi);

    return 0;
}