The Utility of the OR Bitwise Operator

#include <stdio.h> 
# define BV(x) ( 1 << x) 
int main( ) 
{
  // Declare variables
	unsigned char n ; 
	unsigned int val ;
	n = 150;
  // Check whether the 3rd bit is on or off
	if ( ( n & BV(3) ) == BV(3) ) 
		printf( "3rd bit is on\n" ) ; 
	else
	{
		printf ( "3rd bit is off\n" ) ;
    // Put on 3rd bit
		n = n | BV(3) ; 
		printf ( "%d\n", n ) ; 
	}
}