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Bugs & Features
<?php // Surprise surprise! When the 2nd array param of array_diff() contains an elemant with value false, // the result will no longer contain null values. function myIsset($value) { return isset($value); } $arrayWithTrueValue = array( 'null1' => null, 'null2' => null, 'bool' => true, ); $filteredArray = array_filter($arrayWithTrueValue, 'myIsset'); echo "\$arrayWithTrueValue has three elements..\n"; var_dump($arrayWithTrueValue); echo "\$filteredArray has one element (only isset(true) === true)\n"; var_dump($filteredArray); echo "so the difference is an array with two elements..\n"; var_dump(array_diff($arrayWithTrueValue, $filteredArray)); $arrayWithFalseValue = $arrayWithTrueValue; $arrayWithFalseValue['bool'] = false; $filteredArrayWithOnlyFalse = array_filter($arrayWithFalseValue, 'myIsset'); var_dump($arrayWithFalseValue, $filteredArrayWithOnlyFalse, array_diff($arrayWithFalseValue, $filteredArrayWithOnlyFalse));
Output for 4.3.0 - 7.1.0
$arrayWithTrueValue has three elements.. array(3) { ["null1"]=> NULL ["null2"]=> NULL ["bool"]=> bool(true) } $filteredArray has one element (only isset(true) === true) array(1) { ["bool"]=> bool(true) } so the difference is an array with two elements.. array(2) { ["null1"]=> NULL ["null2"]=> NULL } array(3) { ["null1"]=> NULL ["null2"]=> NULL ["bool"]=> bool(false) } array(1) { ["bool"]=> bool(false) } array(0) { }