Q. PHP program to find whether a number is power of two or not.

Here you will find an algorithm and program in PHP to find whether the given number is power of 2 or not. Now first let us understand what power of two means.

Explanation : In mathematics, a power of two is a number of the form 2^n where n is an integer. Here we use a mathematical concept of Logarithm, The most simple method for finding whether a number is power of two or not is to simply take the log of the number on base 2 and if you get an integer then the number is the power of 2.

For Example : 256, when we take log of 256 to the base 2 we get 8 which is integer, hence 256 is power of 2.

START
Step 1 → Take integer variable num
Step 2 → find out the log number with base 2
Step 3 → if outcome is integer then DISPLAY number is power of 2.
Step 4 → Otherwise, DISPLAY number is not power of 2.
STOP

PHP Program to Find Whether a Given Number is Power of 2

function Log2($x) 
{ 
    return (log10($x) / log10(2)); 
} 
 
function find_power_of_two($num) 
{ 
    return (ceil(Log2($num)) ==  floor(Log2($num))); 
} 

$num=256;
if(find_power_of_two($num)) 
    echo "$num is the power of two"; 
else
    echo "$num is not the power of two"; 

Output

256 is the power of two.