关于PHP数组合并

The union operator did not behave as I thought it would on first glance. It implements a union (of sorts) based on the keys of the array, not on the values.

PHP中合并操作符”+”跟我的第一印象认为的不太一样，它是基于key集合实现的数组合并，并不是value

For instance:

<?php
    $a = array('one','two');
    $b=array('three','four','five');

    //not a union of arrays' values
    echo '$a + $b : ';
    print_r ($a + $b);

    //a union of arrays' values
    echo "array_unique(array_merge($a,$b)):";
    // cribbed from http://oreilly.com/catalog/progphp/chapter/ch05.html
    print_r (array_unique(array_merge($a,$b)));
?>

output

$a + $b : Array
(
    [0] => one
    [1] => two
    [2] => five
)

array_unique(array_merge(Array,Array)):Array
(
    [0] => one
    [1] => two
    [2] => three
    [3] => four
    [4] => five
)