Find the Sum of Digits of the Whole Number

# include <stdio.h>

int rsum ( int ) ; 

int main( )
{
	// Declare variables
	int  num, sum ;
	// Initialize variables
	num = 327;
	// Call function and display the value
	sum = rsum ( num ) ;  
	printf ( "Sum of digits = %d\n", sum ) ;
	return 0 ;
}

int rsum ( int  n )  
{
	// Declare variables
	int  s, d ;

	while ( n != 0 )
	{
		// Store the right-most digit
		d = n % 10 ;  
		// Remove the right-most digit
		n = n / 10 ;
		// Add the digit value in the rest of the sum
		s = s+ d ;
	}
	// Return sum to the calling point
	return ( s ) ;
}