The array_diff_uassoc Function

The array_diff_uassoc function compares arrays and returns elements from the first array that are absent in subsequent arrays. In this case, key comparison is performed using a user-defined callback function.

Syntax

phparray_diff_uassoc(array $array1, array $array2, ..., callable $key_compare_func): array

Example

Let's compare two arrays with a user-defined function for key comparison:

php<?php
  function compareKeys($a, $b) {
    if ($a === $b) return 0;
    return ($a > $b) ? 1 : -1;
  }

  $array1 = ['a' => 1, 'b' => 2, 'c' => 3];
  $array2 = ['a' => 1, 'b' => 5, 'd' => 4];

  $res = array_diff_uassoc($array1, $array2, 'compareKeys');
  print_r($res);
?>

Code execution result:

php[
  'b' => 2,
  'c' => 3,
]

Example

Case-sensitive key comparison:

php<?php
  function caseSensitiveCompare($a, $b) {
    return strcasecmp($a, $b);
  }

  $array1 = ['A' => 1, 'B' => 2, 'C' => 3];
  $array2 = ['a' => 1, 'b' => 2, 'd' => 4];

  $res = array_diff_uassoc($array1, $array2, 'caseSensitiveCompare');
  print_r($res);
?>

Code execution result:

php[
  'C' => 3
]

See Also