#include <stdio.h>

#define PI 3.141592653589793

void circumference(double radius)
{
    double result = 2 * PI * radius;

    printf("\nCircle circumference\n");
    printf("Radius = %.2f\n", radius);
    printf("Circumference = %.2f\n", result);
}

void circleArea(double radius)
{
    double result = PI * radius * radius;

    printf("\nCircle area\n");
    printf("Radius = %.2f\n", radius);
    printf("Area = %.2f\n", result);
}

void sphereVolume(double radius)
{
    double result = (4.0 / 3.0) * PI * radius * radius * radius;

    printf("\nSphere volume\n");
    printf("Radius = %.2f\n", radius);
    printf("Volume = %.2f\n", result);
}

int main(void)
{
    void (*calculations[3])(double) =
    {
        circumference,
        circleArea,
        sphereVolume
    };

    int choice;
    double radius;

    printf("Enter 0 to calculate circle circumference\n");
    printf("Enter 1 to calculate circle area\n");
    printf("Enter 2 to calculate sphere volume\n");

    scanf("%d", &choice);

    if (choice < 0 || choice > 2)
    {
        printf("Invalid choice.\n");
    }
    else
    {
        printf("Enter radius: ");
        scanf("%lf", &radius);

        (*calculations[choice])(radius);
    }

    return 0;
}