Merging two multidimensional arrays on specific key

Let's say I have following arrays:

Array
    (
        [0] => Array
            (
                [id] => 5
                [name] => Education
            )

        [1] => Array
            (
                [id] => 4
                [name] => Computers
            )

        [3] => Array
            (
                [id] => 7
                [name] => Science

        [4] => Array
            (
                [id] => 1
                [name] => Sports
            )
    )

And the second one:

Array
    (
        [0] => Array
            (
                [id] => 1
                [title] => Sport
            )

        [1] => Array
            (
                [id] => 7
                [title] => Sci
            )

        [3] => Array
            (
                [id] => 4
                [title] => Comp

        [4] => Array
            (
                [id] => 5
                [title] => Edu
            )
    )

And desired output is:

Array
    (
        [0] => Array
            (
                [id] => 5
                [name] => Education
                [title] => Edu
            )

        [1] => Array
            (
                [id] => 4
                [name] => Computers
                [title] => Comp
            )

        [3] => Array
            (
                [id] => 7
                [name] => Science
                [title] => Sci

        [4] => Array
            (
                [id] => 1
                [name] => Sports
                [title] => Sport
            )
    )

I have managed to merge these arrays with simply:

foreach($first as $key => $value){
    $result[$key] = array_merge($first[$key], $second[$key]);
}

But the output is not combined correctly:

Array
    (
        [0] => Array
            (
                [id] => 5
                [name] => Education
                [title] => Sport
            )

        [1] => Array
            (
                [id] => 4
                [name] => Computers
                [title] => Sci
            )

        [3] => Array
            (
                [id] => 7
                [name] => Science
                [title] => Comp

        [4] => Array
            (
                [id] => 1
                [name] => Sports
                [title] => Edu
            )
    )

The problem is I would like to merge these arrays on the same id. Desired output sorting should be same as in the first array.

How can I achieve this? Any help is much appreciated.

Solution 1:

You can just do a nested loop and check if the id values match, then add title to $first (or name to $second)

foreach($first as $key => $value){
    foreach($second as $value2){
        if($value['id'] === $value2['id']){
            $first[$key]['title'] = $value2['title'];
        }               
    }
}

Solution 2:

You code works fine. Your expectations are simply incorrect. For example in one array 4th element id holds 1 but in another array, 4th element id is 5, so your "merge these arrays on the same id" makes no sense as by merging 4th elements into one you also merge their children, and since id is used in both arrays, once value HAVE TO be gone as there cannot be two equal keys in array.

EDIT

you have to merge manually as PHP functions merge based on keys while you want to merge based on content:

$result = array();
foreach( $arrayA as $keyA => $valA ) {
  foreach( $arrayB as $keyB => $valB ) {
     if( $valA['id'] == $valB['id'] ) {
       $result[$keyA] = $valA + $valB;

       // or if you do not care output keys, just
       // $result[] = $valA + $valB;
     }
  }
}