gmp_popcount

Population count (PHP 4 >= 4.0.4, PHP 5)
int gmp_popcount ( resource a )

Return the population count of a.

例 686. 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 printout of the above program will be:

3
7