Online PHP editor | refs for MO7j4

<?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));