PHP中array_merge函数与array+array的区别

2019年9月18日09:52:36 发表评论 4 次浏览

PHP中array_merge函数与array+array的区别
在PHP中可以使用array_merge函数和两个数组相加array+array的方式进行数组合并,但两者效果并不相同,下面为大家介绍两者具体的使用区别.

区别如下:

当下标为数值时,array_merge()不会覆盖掉原来的值,但array+array合并数组则会把最先出现的值作为最终结果返回,而把后面的数组拥有相同键名的那些值“抛弃”掉(不是覆盖).

当下标为字符时,array+array仍然把最先出现的值作为最终结果返回,而把后面的数组拥有相同键名的那些值“抛弃”掉,但array_merge()此时会覆盖掉前面相同键名的值.

例子1:

代码:

$arr1 = ['PHP', 'apache'];
$arr2 = ['PHP', 'MySQl', 'HTML', 'CSS'];
$mergeArr = array_merge($arr1, $arr2);
$plusArr = $arr1 + $arr2;
var_dump($mergeArr);
var_dump($plusArr);

结果
$mergeArr:

array (size=6)
0 => string 'PHP' (length=3)
1 => string 'apache' (length=5)
2 => string 'PHP' (length=3)
3 => string 'MySQl' (length=5)
4 => string 'HTML' (length=4)
5 => string 'CSS' (length=3)

$plusArr

array (size=4)
0 => string 'PHP' (length=3)
1 => string 'apache' (length=5)
2 => string 'HTML' (length=4)
3 => string 'CSS' (length=3

例子2:

代码:

$arr1 = ['PHP', 'a'=>'MySQl'];
$arr2 = ['PHP', 'MySQl', 'a'=>'HTML', 'CSS'];
$mergeArr = array_merge($arr1, $arr2);
$plusArr = $arr1 + $arr2;
var_dump($mergeArr);
var_dump($plusArr);

结果
$mergeArr:

array (size=5)
0 => string 'PHP' (length=3)
'a' => string 'HTML' (length=4)
1 => string 'PHP' (length=3)
2 => string 'MySQl' (length=5)
3 => string 'CSS' (length=3)

$plusArr

array (size=4)
0 => string 'PHP' (length=3)
'a' => string 'MySQl' (length=5)
1 => string 'MySQl' (length=5)
2 => string 'CSS' (length=3)

例子3:

代码:

$arr1 = ['PHP', 'a'=>'MySQl','6'=>'CSS'];
$arr2 = ['PHP', 'MySQl', 'a'=>'HTML', 'CSS'];
$mergeArr = array_merge($arr1, $arr2);
$plusArr = $arr1 + $arr2;
var_dump($mergeArr);
var_dump($plusArr);

结果:

$mergeArr

array (size=6)
0 => string 'PHP' (length=3)
'a' => string 'HTML' (length=4)
1 => string 'CSS' (length=3)
2 => string 'PHP' (length=3)
3 => string 'MySQl' (length=5)
4 => string 'CSS' (length=3)

$plusArr

array (size=5)
0 => string 'PHP' (length=3)
'a' => string 'MySQl' (length=5)
6 => string 'CSS' (length=3)
1 => string 'MySQl' (length=5)
2 => string 'CSS' (length=3)

相信通过上边三个例子大家已经非常清楚array_merge()函数和array+array数组相加的区别了吧。

阿修罗

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