array_merge与+的区别

<?php
$a = array("a"=>1,"b"=>2,"c"=>3);
$b = array("aa"=>1,"22"=>2,"cc"=>3);
$data = array_merge($a,$b);
print_r($data);
$data2 = $a + $b;
print_r($data2);
?>

结果：

Array
(
    [a] => 1
    [b] => 2
    [c] => 3
    [aa] => 1
    [0] => 2
    [cc] => 3
)
Array
(
    [a] => 1
    [b] => 2
    [c] => 3
    [aa] => 1
    [22] => 2
    [cc] => 3
)

array_merge：数字键名将会被重新编号！如果你想完全保留原有数组并只想新的数组附加到后面，用+运算符。