PHP两个数组相加

在PHP中，当两个数组相加时，会把第二个数组的取值添加到第一个数组上，同时覆盖掉下标相同的值：

<?php
$a = array("a" => "apple", "b" => "banana");
$b = array("a" => "pear", "b" => "strawberry", "c" => "cherry");
echo "a: </br> ";
print_r($a);
echo " </br> b:   </br>";
print_r($b);
$c = $a + $b;
echo " </br>Union of \$a and \$b: </br>";
var_dump($c);

$c = $b + $a;
echo " </br>Union of \$b and \$a:  </br>";
var_dump($c);

$a += $b;
echo " </br>Union of \$a += \$b:  </br>";
var_dump($a);

?>

以上的输出结果为：