I have used Code::blocks 12 compiler for debugging purpose. But you can use any C programming language compiler as per your availability.

#include <stdio.h>
 
// Function declaration
double cube(double num);
 
int main()
{
    int num;
    double c;
 
    //Inputting number from user
    printf("Enter any number: ");
    scanf("%d", &num);
 
    c = cube(num);
 
    printf("Cube of %d is %.2f", num, c);
 
    return 0;
}
 
//Function to find cube of any number
double cube(double num)
{
    return (num * num * num);
}

Result:

Enter any number: 6

Cube of 6 is 216.00