(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)
gmp_popcount — Population count
The population count of num, as an int.
Example #1 gmp_popcount() example
<?php
$pop1 = gmp_init("10000101", 2); // 3 1's
echo gmp_popcount($pop1) . "\n";
$pop2 = gmp_init("11111110", 2); // 7 1's
echo gmp_popcount($pop2) . "\n";
?>
The above example will output:
3 7