#include

$//$ FORWARD DECLARATIONS

int digitSum$($int number$)$;

int main$($int argc, char $*$ argv$[])$

$\{$

int num;

int sum;

$//$ Prompt for, and receive user input

printf$("$Enter a number whose digits should be summed: $")$;

if $($scanf$("\%$d$",$ &num$)!=1)$

$\{$

printf$("$Sorry$,$ you didn't enter a number.

$")$;

return $1$;

$\}$

$//$ Calculate the sum of the digits of the provided number

sum $=$ digitSum$($num$)$;

$//$ Print out the result.

printf$("$The sum of the digits of $\%$d is $\%$d

$",$ num, sum$)$;

$//$ Return success

return $0$;

$\}$

$/**$

$*$ Calculate and return the sum of the digits of a given number.

$*$

$*$ @param number

$*$ The number whose digits are to be summed

$*$

$*$ @return

$*$ The sum of the number's digits

$*/$

int digitSum$($int number$)$

$\{$

int digit;

int sumOfDigits $=0$;

while $($number $!=0)$

$\{$

$//$ Get the next digit

digit $=$ number $/10$;

$//$ Add this digit to the sum

sumOfDigits $=$ sumOfDigits $+$ digit;

$//$ Prepare for next digit

number $=$ number $/10$;

$\}$

$//$ Give $\text{'}$em the sum

return sumOfDigits;

$\}$