array_diff to compare two associative arrays

Question

I'm confusing array_diff behavior

why genre don't exist on diff array? Do you know how to resolve the matter?

-code

<?php
$array1 = array
(
    'value01' => '0',
    'value02' => 'v2',
    'genre' => '1',
    'type' => 'text',
    'contry' => 'us',
    'data' => '1',
);
$array2 = array
(
    'value01' => 'v1',
    'value02' => 'v2',
    'genre' => '0',
    'type' => 'text',
    'contry' => 'canada',
    'data' => '1',
);

print_r(array_diff($array1,$array2));

My result:

Array
(
    [contry] => us
)

But I expect:

Array
(
    [value01] => 0,
    [genre] => 1,
    [contry] => us,
);

Answer 1

array_diff operates on the values of the array, and ignores the keys.

Because the value of genre in your first array is 1, that means that if the value 1 occurs for any key in the second array, then the genre key will be removed from the first array.

Look at your arrays without the keys, and you'll see what I mean. You essentially have two lists of values, ['0','v2','1','text','us','1'] and ['v1','v2','0','text','canada','1']. The only value from the first list that doesn't appear in the second is 'us'.

I'm guessing you'll probably want to have a look at array_key_diff() or array_diff_assoc().