PHP function array_udiff_assoc() is used to compare the key names and key values ​​of two arrays and return the difference set

Example

Compare the key names and key values ​​of the two arrays (use built-in functions to compare key names, use user custom functions to compare key values), and return the difference set:

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

$a1=array("a"=>"red","b"=>"green","c"=>"blue");
$a2=array("a"=>"red","b"=>"blue","c"=>"green");

$result=array_udiff_assoc($a1,$a2,"myfunction");
print_r($result);
?>

Definition and usage

array_udiff() function is used to compare the key names and key values ​​of two (or more) arrays and return the difference.

Note: This function uses built-in functions to compare key names and user-defined functions to compare key values!

This function compares the key names and key values ​​​​of two (or more) arrays, and returns a difference array, which includes everything in the compared array (array1), but not in any other The key name and key value in the parameter array (array2 or array3, etc.).

Syntax

array_udiff_assoc(array1,array2,array3...,myfunction)

Parameters	Description
array1	Required. The first array to compare with other arrays.
array2	Required. The array to compare to the first array.
array3,...	Optional. Additional array to compare with the first array.
myfunction	Required. A string that defines a callable comparison function. If the first argument is <, =, > and the second argument is, the corresponding comparison function must return an integer of <, =, > 0.

Technical details

Return value:	Returns a difference array, which includes Returns all key names and values ​​that are in the compared array (array1) but not in any other parameter array (array2 or array3, etc.).
PHP version:	5+

##array_udiff_assoc() Returns an array that includes all A value that is in array1 but not in any other parameter array. Note that unlike array_diff() and array_udiff(), key names are also used for comparison. The comparison of array data is performed using the

callback function provided by the user. In this respect, the behavior of array_diff_assoc() is exactly the opposite, which uses the internal function for comparison.

Example

<?php
class cr {
  private $priv_member;
  function cr($val) {
    $this->priv_member = $val;
  }
  static function comp_func_cr($a, $b) {
    if ($a->priv_member === $b->priv_member) return 0;
    return ($a->priv_member > $b->priv_member) ? 1 : -1;
  }
}
$a = array(
  "0.1" => new cr(9) ,
  "0.5" => new cr(12) ,
  0 => new cr(23) ,
  1 => new cr(4) ,
  2 => new cr(-15) ,
);
$b = array(
  "0.2" => new cr(9) ,
  "0.5" => new cr(22) ,
  0 => new cr(3) ,
  1 => new cr(4) ,
  2 => new cr(-15) ,
);
$result = array_udiff_assoc($a, $b, array(
  "cr",
  "comp_func_cr"
));
print_r($result);
?>

Running result:

Array
(
  [0.1] => cr Object
    (
      [priv_member:private] => 9
    )
 
  [0.5] => cr Object
    (
      [priv_member:private] => 12
    )
 
  [0] => cr Object
    (
      [priv_member:private] => 23
    )
)

In the above example, you can see that the key-value pair "1" => new cr(4) appears in two arrays at the same time in and therefore not in the output of this function.

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