Pay attention to the example of using string operator at script as following:
File name: arrayoperator.php
<html>
<head>
<title>Array Operator</title>
</head>
<body>
<h1>Array Operator</h1>
<?
$x = array ("x" => "black", "y" => "white");
$y = array ("x" => "yellow", "y" => "green", "z" => "red");
$z = $x + $y;
var_dump ($z);
?>
</body>
</html>