Question

How to determining if an integer is a power of 2 in PHP

Answer 1

function print_bits($n) {
    for ($i = 7; $i >= 0; $i--) {
        echo ($n >> $i) & 1;
    }
    echo "<br />";
}
  
$n = 16; 
   
print_bits($n);
print_bits($n - 1);
print_bits($n & ($n - 1));
   
$b = ($n & ($n - 1)) == 0;
       
echo $b;
 
 
   
/*
run:
        
00010000
00001111
00000000
1
       
*/

 

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