Question

I’m trying to compare two 2D arrays in PHP and my head is hurting with all the recursion – this’ll probably be obvious to someone who’s used to it.

I have two 2D arrays which look like this, called $submittedArray2D and $dbArray:

{
    [0] => {
        [0] => 'name'
        [1] => 'sectors'
        [2] => 'address'
        [3] => 'url'
    }
    [1] => {
        [0] => 'name'
        [1] => 'sectors'
        [2] => 'address'
        [3] => 'url'
    }
    ...       
}

$submittedArray2D comes from user input, while $dbArray holds what is already in the database.

I want to compare them to see if any of the values have been updated in $submittedArray2D, and save those changes to $dbArray accordingly.

I also want to pass any changed addresses to a separate function for geocoding, the results of which will be stored in another database field, where the keys reference the same entry in $dbArray (so $geocode[4] refers to $dbArray[4], for example).

I’ve tried out some foreach statements to go through the arrays sequentially, but this breaks down if one of the entries has been removed from the middle of the array, because the two arrays are no longer in sequence. I’m wondering whether some kind of ID for each array entry might make sense, but I’m not sure where to start.

Any ideas or pointers would be much appreciated!

Answer 1

I managed it in the end by storing a unique ID alongside each array element, that was it was possible to loop through and check whether that ID existed in the comparator array and then check whether the address had changed, and if so store the change (along with the ID) in a separate array for processing.