如何在PHP中合并两个数组

Question

I have problem when try to merge two array in PHP.For example:

$array1 = Array
(
    [0] => stdClass Object
        (
            [user_id] => 1
            [count] => 6.5
        )
)

and array two follow:

 $array2 = Array
    (
        [0] => stdClass Object
            (
                [name] => abc
                [user_id] => 1
            ),
        [1] => stdClass Object
        (
            [name] => xyz
            [user_id] => 2
        ),
    )

I want to merge two array above follow:

$array3 = Array
(
    [0] => stdClass Object
        (
            [name] => abc
            [user_id] => 1
            [count] => 6.5
        ),
    [1] => stdClass Object
    (
        [name] => xyz
        [user_id] => 2
        [count] => 0 //set default = 0 if not exist count
    ),
)

So what can I will do, anyone?

Answer 1

If this data is coming from a database then chances are the easiest way to achieve the result is using a join on your database query.

However - here's how you can do it with PHP:

Firstly you want to remap $array1 to user the user ID as its key. This way you avoid needing to nest a loop inside a loop to find the count, and can reference it immediately via the user ID which exists in both arrays:

// Re-map keys for array 1 so you don't have to loop it every time
$temp = array();
foreach ($array1 as $key => $values) {
    $temp[$values->user_id] = $values;
}
$array1 = $temp

Here's an example of what $array1 looks like after you've done this.

Next, construct your $array3 based on $array2 with the added count from $array1 if it exists, otherwise assign zero by default:

// Construct your output array
$array3 = array();    
foreach ($array2 as $values) {
    $values->count = array_key_exists($values->user_id, $array1)
        ? $array1[$values->user_id]->count
        : 0;
    $array3[] = $values;
}

Your output from $array3 will then look like this .