Write a PHP program to check if a given positive integer is a power of two.

power_of_two.php

<?php

/**
* Write a PHP program to check if a given positive integer is a power of two.
* Input : 4	
*
*
* Example (positive):
* n = 32	
* than in binary representation
* n = 100000
* Then n - 1 = 011111 So if you take n - 1 & n you get 0.
* Example (negative):	
* n = 6
* than in binary representation
* n = 110
* Now
* n - 1 = 101
* So ((n - 1) & n) == 100 > 0.
*/

function is_Power_of_two($n)
{
   if(($n & ($n - 1)) == 0)
    {
		return "$n is power of 2";
    }
   else
    {
		return "$n is not power of 2";
    }
}
print_r(is_Power_of_two(4)."\n");
print_r(is_Power_of_two(37)."\n");
print_r(is_Power_of_two(16)."\n");
?>