/*
   Lab : Lab3 
   Day : Tuesday  [ 12 Aug 08 ]

   Problem Number: 02
   Problem Title : Exact power of 2 
   
   Theory : 

    	when you successively multiply 2 to 1 you would generate exact powers of 2

     	The problem requires a while loop 
        that will successively generate exact powers of 2 
	and with every exact power, compare the num 
	Ther can be three cases
	
		1. so far generated power of 2 and num are same
			Than print " Number is exact power of 2" and 
			end the program
		2. num is less than  so far generated powre of 2 '
			Than print " Number is not exact power of 2" and 
			end the program
		3. so far generated power of 2 ( number obtained by successively multiplying 2 to 1 )
		   becomes negative 
			Then also print " Number is not exact power of 2" and 
			end the program
			because overflow had occured meaning num is not exact power of 2
*/

class sol_lab3_prob02{

   	public static void main(String args[])
	{
                // Declare a variable num of type int and assign it some positive value
  		int num; 
		num = 128; // done 

             	// create some more variable
		int i = 0; // an integer that represents what is current power that is raised on 2
		int n = 1; // an integer that represents value whan 2 is raised power i 

		while(true)
		{
			if( n == num )
			{
				System.out.println("[ Number is exact power of 2] it is 2^" + i); //print message
				return; // and exit from program
			}

			if( n > num )
			{
				System.out.println(" Number is NOT exact power of 2"); //print message
				return; // and exit from program
			}

			if( n <= 0 )
			{
				System.out.println(" Number is NOT exact power of 2 : OVERFLOW"); //print message
				return; // and exit from program
			}
						
			i = i + 1; 
			n = n * 2; // create next power of 2 for testing
		}		
	}	
}