Question

For example, I have $dates1 and $dates2 shown below, and want to create $dates3, which keeps all dates in $dates1, and adds any unique dates in $dates2, ignoring any duplicates. The arrays contain other values but I’m just showing the dates because that’s what I want to merge/sort on.

$dates1=

Array
(
[0] => Array
    (
        [day] => 2012-01-01
        [foo] => "bar"
    )

[1] => Array
    (
        [day] => 2012-01-02
        [foo] => "bar"
    )

[2] => Array
    (
        [day] => 2012-01-03
        [foo] => "bar"
    )
)

$dates2=

Array
(
[0] => Array
    (
        [day] => 2011-12-31
    )

[1] => Array
    (
        [day] => 2012-01-01
    )

[2] => Array
    (
        [day] => 2012-01-02
    )
[3] => Array
    (
        [day] => 2012-01-03
    )
[4] => Array
    (
        [day] => 2012-01-04
    )
)

So I would like to merge $dates2 into $dates1, ignoring any duplicates, to make $dates3:

Array
(
[0] => Array
    (
        [day] => 2011-12-31
    )

[1] => Array
    (
        [day] => 2012-01-01
        [foo] => "bar"
    )

[2] => Array
    (
        [day] => 2012-01-02
        [foo] => "bar"
    )
[3] => Array
    (
        [day] => 2012-01-03
        [foo] => "bar"
    )
[4] => Array
    (
        [day] => 2012-01-04
    )
)

Answer 1

I’m not sure I understand you correctly, do you mean something like this?

    $old_array = array_merge($dates1, $dates2);
    $new_array = array();
    foreach ($old_array as $item){
        if (!array_key_exists($item['day'], $new_array)){
            $new_array[$item['day']] = $item;
        }
    }
    return $new_array;