PHP array_diff_uassoc() Function
Quick summary: The PHP array_diff_uassoc() function compares the values and keys of two (or more) arrays using a user-defined key comparison function, and returns the differences.
PHP array_diff_uassoc() Syntax
array_diff_uassoc(array $array, array ...$arrays, callable $key_compare_func): arrayPHP
PHP array_diff_uassoc() Basic examples
$a = ['a'=>1,'b'=>2];
$b = ['A'=>1,'b'=>2];
$result = array_diff_uassoc($a,$b, 'strcasecmp');
print_r($result);PHP
Output:
Array ( )Compares keys using user-defined callback.
PHP array_diff_uassoc() Real-world usage
function cmp($a,$b){ return strcmp($a,$b); }
$a=['x'=>1];
$b=['y'=>1];
print_r(array_diff_uassoc($a,$b,'cmp'));PHP
Output:
Array ( [x] => 1 )Custom key comparison logic.
PHP array_diff_uassoc() Edge cases
array_diff_uassoc($a,$b,null);PHP
Output:
WarningCallback must be valid and callable.
PHP array_diff_uassoc() Common mistakes
Wrong callback return value
Callback must return integer <0, 0, >0.
Incorrect
array_diff_uassoc($a,$b,fn()=>true);Correct
array_diff_uassoc($a,$b,fn($x,$y)=>$x<=>$y);Return proper comparison integer.
PHP array_diff_uassoc() Frequently Asked Questions
What does array_diff_uassoc() do?
Computes array diff with user-defined key comparison.
Use case?
Custom key comparison.
Callback required?
Yes.
Common mistake?
Wrong callback signature.
Performance?
Slower due to callback.
Return type?
Array.
Safe?
Yes.
Alternative?
array_diff_assoc().
Handles values?
Yes.
Key comparison customizable?
Yes.
Best practice?
Use simple callbacks.
Used in advanced filtering?
Yes.