GMP Functions
PHP Manual

gmp_popcount

Population count

Description

int gmp_popcount ( resource $a )

Get the population count.

Parameters

a

It can be either a GMP number resource, or a numeric string given that it is possible to convert the latter to a number.

Return Values

The population count of a, as an integer.

Examples

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