English
English
In PHP, the array_intersect_uassoc function is used to compare the keys and values of two arrays, returning the part where the key-value pairs are the same in the two arrays. What makes it different from array_intersect_assoc is that array_intersect_uassoc allows users to customize the comparison function of keys.
The function is defined as follows:
array_intersect_uassoc(array $array1, array $array2, callable $key_compare_func): array
$array1 and $array2 are two arrays participating in the comparison.
$key_compare_func is a user-defined function for comparing keys, and the return value is similar to strcmp .
When the order of key-value pairs of arrays is inconsistent, array_intersect_uassoc will still compare based on the corresponding relationship between keys and values. That is, the keys and values must be "equal" to appear in the result, regardless of their order in the array.
For example:
<?php
$array1 = [
'a' => 1,
'b' => 2,
];
$array2 = [
'b' => 2,
'a' => 1,
];
$result = array_intersect_uassoc($array1, $array2, 'strcmp');
print_r($result);
Output:
Array
(
[a] => 1
[b] => 2
)
Even if the order of key-value pairs in $array2 is different from $array1 , the result still contains all matching key-value pairs.
Assuming your custom comparison function is sensitive to order, it may cause matching failures. The default string comparison function strcmp is order-independent, but if the comparison function you wrote contains order or other conditions, the result may be different.
If you want to ensure that the key-value pairs can match correctly even if they are in different orders, you can follow the following suggestions:
Make sure that the comparison function only compares the values of the key itself and does not bring in sequential related logic.
First sort the keys of the array , and then use array_intersect_uassoc for comparison to avoid the impact of order differences.
Example: Sort first and then compare
<?php
$array1 = [
'b' => 2,
'a' => 1,
];
$array2 = [
'a' => 1,
'b' => 2,
];
// Sort the keys
ksort($array1);
ksort($array2);
$result = array_intersect_uassoc($array1, $array2, 'strcmp');
print_r($result);
In this way, even if the initial order is different, the order will be consistent after sorting, avoiding the possible unexpected results of order differences.
array_intersect_uassoc compares keys and values, and the order itself does not affect the matching result.
Custom key comparison functions should avoid including sequentially related logic.
To be on the safe side, you can use ksort() to sort the arrays participating in the comparison first to ensure uniform order.
<?php
$array1 = [
'b' => 2,
'a' => 1,
];
$array2 = [
'a' => 1,
'b' => 2,
];
ksort($array1);
ksort($array2);
$result = array_intersect_uassoc($array1, $array2, 'strcmp');
print_r($result);
