C program to find cube of a number using function

Write a C program to input any number from user and find cube of the given number using function. How to find cube of a given number using function in C programming. Write a C function to find cube of a given number.

Required knowledge

Basic C programming, Functions, Returning value from function

Declare function to find cube of a number

Cube of a number num is cube = num * num * num. This is easy, but we need to write a separate function for this simple statement.

  1. First assign a meaningful name to the function, say cube().
  2. The function should accept a number whose cube is to be calculated. Hence, function definition is cube(double num).
  3. Finally, the function should return cube of num passed. Hence, return type of function should be double.

    After observing above points function declaration looks like double cube(double num);

Note: Instead of taking double as parameter and return type. You can also use int, float or any other integer/fractional types. However, double fits best for the above requirement.

Program to find cube using function

 * C program to find cube of any number using function
#include <stdio.h>

/* Function declaration */
double cube(double num);

int main()
    int num;
    double c;
    /* Input number to find cube 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);

Important note: Inside cube() function you can also use a temporary variable to store cube of num. Which is

double cube(double num)
    double c = num * num * num;
    return c;

However, the above approach is not worth. In addition, it increases complexity to declare a useless variable c. Instead we can directly return cube of num as in first approach.

%.2f prints fractional numbers up to 2 decimal places. You can also use %f, to print fractional numbers up to 6 decimal places (default).


Enter any number: 5

Cube of 5 is 125.00