Online PHP editor | output for 621Rf

<?php $rose = "black"; ${"rose"} = "white"; $rose = "red"; print_r(${"rose"}); echo "\n\n"; /** Parse error: syntax error, unexpected '123' (T_LNUMBER), expecting variable (T_VARIABLE) or '{' or '$' $123 = 456; var_dump($123); **/ ${"123"} = "white"; var_dump(${"123"}); echo '<pre>'; //var_dump(get_defined_vars()); if( in_array($("123"),get_defined_vars())){ echo "\${"123"} in array"; } echo "\n\n"; $arr{"246a"} = 99; var_dump($arr); $o = (object) $arr; var_dump($o); echo $o->{"246a"},"\n\n"; class x extends stdClass { public $val; function Show($n){ $this->val = $n; return $this->val; } } $s = new x(); echo $s->Show(100),"\n"; var_dump($s); var_dump($s instanceof stdClass);