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php array bitwise

Posted by: admin July 12, 2020 Leave a comment

Questions:

if I have an array of flags and I want to combine them with a bitwise conjunction

ie:

$foo = array(flag1, flag2);

into

$bar = flag1 | flag2;

Does PHP have any good functions that will do this nicely for me already?

How to&Answers:

The array_reduce will reduce an array to a single value for you:

$res = array_reduce($array, function($a, $b) { return $a | $b; }, 0);

Reduce is also sometimes called fold (fold left or fold right) in other languages.

Answer:

You could do it like so

$bar = $foo[0] | $foo[1]

If the size of your array is unknown you could use array_reduce like this

// in php > 5.3
$values = array_reduce($flagArray, function($a, $b) { return $a | $b; });
// in php <= 5.2
$values = array_reduce($flagArray, create_function('$a, $b', 'return $a | $b'));

Answer:

$values = array_reduce($foo,function($a,$b){return is_null($a) ? $b : $a | $b;});

PHP < 5.3 (no closures), either of these two:

function _mybitor($a,$b){return is_null($a) ? $b : $a | $b;}
$values = array_reduce($foo,'_mybitor');

or

$values = array_reduce($foo,create_function('$a,$b','return is_null($a) ? $b : $a | $b;'));

);

Answer:

A simple suggestion to the accepted answer: create a sibling to array_sum.

function array_or (array $array): int {
    return array_reduce($array, function($a, $b) { return $a | $b; }, 0);
  }