Solution Review: Turn On the 3rd and 5th Bits

# include <stdio.h>
# define _BV(x) ( 1 << x )
void showbits ( unsigned char n ) ;
short unsigned int onBits (short unsigned int num) ; 

int main( )
{
	unsigned  char  b;
	short unsigned int num ; 
	num = 211;
	onBits (num);
}

// Shows the bits in a number
void showbits ( unsigned char n )
{
	int i ;
	unsigned char j, k, andmask ; 
	for ( i = 7 ; i >= 0 ; i-- )
	{
		j = i ;
		andmask = 1 << j ; 
		k = n & andmask ;
		k == 0 ? printf ( "0" ) : printf ( "1" ) ;
	}
}

short unsigned int onBits (short unsigned int num) 
{
	unsigned  char  a, mask ;  
	num = num & 0x00FF ; 
	a = num ; 
	showbits (a);
	printf("\n");
	// Turns on 3rd bit if it is off
	mask = _BV( 3 ) ;
	if ( ( a & mask ) != mask ) 
		a = a | mask ;
	// Turns on 5th bit if it is off
	mask = _BV( 5 ) ;
	if ( ( a & mask ) != mask ) 
		a = a | mask ;
	showbits (a);
	printf("\n");
	return a;	
}