如何将字符串数组与数字数组进行比较？

Question

dear users of StackOverflow. There is some problem.

Array 1:
array: 3 [▼
   0 => "8"
   1 => "13"
   2 => "15"
]

Array 2:
array: 16 [▼
   0 => 7
   1 => 8
   2 => 9
]

array_diff does not work, because in the first number, in the second string.

Please suggest any ideas for solving the issue. I will be happy with any comment. Many thanks.

Answer 1

You can use array_udiff to compare the arrays using a user-defined callback which converts the values to ints before comparing:

$array1 = array('8', '13', '15');
$array2 = array(7, 8, 9);
$diffs = array_udiff($array1, $array2, function ($a, $b) { return (int)$a - (int)$b; });
print_r($diffs);

Output:

Array
(
    [1] => 13
    [2] => 15
)

Update

It has been pointed out that the desired output hasn't been specified, so here is how to get all unique values:

$diffs1 = array_udiff($array1, $array2, function ($a, $b) { return (int)$a - (int)$b; });
$diffs2 = array_udiff($array2, $array1, function ($a, $b) { return (int)$a - (int)$b; });
$diffs = array_merge($diffs1, $diffs2);
print_r($diffs);

Output:

Array
(
    [0] => 13
    [1] => 15
    [2] => 7
    [3] => 9
)

and all matching values using array_uintersect:

$same = array_uintersect($array1, $array2, function ($a, $b) { return (int)$a - (int)$b; });
print_r($same);

Output:

Array
(
    [0] => 8
)

Note

In PHP7 there is now the spaceship operator (<=>) which can also be used in the comparison function e.g.

$diffs = array_udiff($array1, $array2, function ($a, $b) { return (int)$a <=> (int)$b; });