Online PHP editor | output for LP3Qe

<?php class SomeHelperClass { public $_arr = []; public function addValue($value, $key = null): void { if ($key !== null) { $this->_arr[$key] = $value; } elseif (!$this->_arr) { $this->_arr[] = $value; } else { $this->_arr[max(array_keys($this->_arr)) + 1] = $value; } } } $test = new SomeHelperClass; var_export($test->_arr); echo "\n"; $test->addValue(1); var_export($test->_arr); echo "\n"; $test->addValue(2); var_export($test->_arr); echo "\n"; $test->addValue(3, 4); var_export($test->_arr); echo "\n"; $test->addValue(4, 3); var_export($test->_arr); echo "\n"; $test->addValue(5); var_export($test->_arr);