gmp_popcount

(PHP 4 >= 4.0.4, PHP 5, PHP 7)

gmp_popcountConteggio della popolazione

Descrizione

gmp_popcount ( resource $a ) : int

Restituisce il conteggio della popolazione di a.

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phpmanual at headbank dot co dot uk
11 months ago
If you don't have gmp extension enabled (or don't want to use it for any reason), you can get popcount of an int using decbin() and substr_count().

<?php
$int1
= 133;
$bin1 = decbin($int1); // "10000101"
echo substr_count($bin1, "1");

// Result: 3
?>

Being a string-comparison this is far less efficient than gmp_popcount() (for which there is a dedicated instruction on most if not all modern processors), but may be handy if gmp is unavailable, or in non-performance-critical code that doesn't otherwise need it.
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