Online PHP editor | output for AkSgW

<?php $myVar = "original"; testFunc([$myVar]); echo "Variable value: $myVar <br>"; // Output is: "Variable value: original" testFunc([&$myVar]); echo "Variable value: $myVar <br>"; // Output is: "Variable value: changed" testFunc([&$undefinedVar]); echo "Variable value: $undefinedVar<br>"; // Output is: "Variable value: changed" @testFunc([$undefinedVar_2]); echo @"Variable value: $undefinedVar_2<br>"; // Output is: "Variable value: " function testFunc( array $arr ) : void { ob_start(); var_dump($arr); if(preg_match('#&(int|NULL|string)#',ob_get_clean())){ print 'is ref '; var_dump($arr); } if ( !is_array($arr) || count($arr) == 0 ) return; $arr[0] = 'changed'; }