PHP array_intersect_uassoc() Function
Quick summary: The PHP array_intersect_uassoc() function computes the intersection of arrays with additional index check performed by a user-defined callback function.
PHP array_intersect_uassoc() Syntax
array_intersect_uassoc(array $array, array ...$arrays, callable $key_compare_func): arrayPHP
PHP array_intersect_uassoc() Basic examples
$a = ['a'=>1,'b'=>2];
$b = ['A'=>1,'b'=>3];
$result = array_intersect_uassoc($a, $b, 'strcasecmp');
print_r($result);PHP
Output:
Array ( [a] => 1 )Keys are compared using a custom callback.
PHP array_intersect_uassoc() Real-world usage
function cmp($x, $y){ return strcmp($x, $y); }
$a=['id'=>1,'name'=>'John'];
$b=['id'=>1,'name'=>'Jane'];
print_r(array_intersect_uassoc($a, $b, 'cmp'));PHP
Output:
Array ( [id] => 1 )Custom key comparison logic.
PHP array_intersect_uassoc() Edge cases
array_intersect_uassoc($a, $b, null);PHP
Output:
WarningThe callback must be a valid callable.
PHP array_intersect_uassoc() Common mistakes
Returning boolean from callback
Callback must return an integer (<0, 0, >0).
Incorrect
array_intersect_uassoc($a, $b, fn()=>true);Correct
array_intersect_uassoc($a, $b, fn($x, $y)=>$x<=>$y);Return proper comparison integer.
PHP array_intersect_uassoc() Frequently Asked Questions
What does array_intersect_uassoc() do?
Intersection with user-defined value comparison and index check.
Use case?
Custom strict intersection.
Callback required?
Yes.
Handles keys?
Yes.
Common mistake?
Wrong callback.
Return type?
Array.
Performance?
Moderate.
Safe?
Yes.
Alternative?
array_intersect_assoc().
Flexible?
Yes.
Best practice?
Keep callbacks simple.
Used in configs?
Yes.