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array_diff_assoc

(PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)

array_diff_assocComputes the difference of arrays with additional index check

Description

array_diff_assoc(array $array, array ...$arrays): array

Compares array against arrays and returns the difference. Unlike array_diff() the array keys are also used in the comparison.

Parameters

array

The array to compare from

arrays

Arrays to compare against

Return Values

Returns an array containing all the values from array that are not present in any of the other arrays.

Changelog

Version Description
8.0.0 This function can now be called with only one parameter. Formerly, at least two parameters have been required.

Examples

Example #1 array_diff_assoc() example

In this example you see the "a" => "green" pair is present in both arrays and thus it is not in the output from the function. Unlike this, the pair 0 => "red" is in the output because in the second argument "red" has key which is 1.

<?php
$array1 
= array("a" => "green""b" => "brown""c" => "blue""red");
$array2 = array("a" => "green""yellow""red");
$result array_diff_assoc($array1$array2);
print_r($result);
?>

The above example will output:

Array
(
    [b] => brown
    [c] => blue
    [0] => red
)

Example #2 array_diff_assoc() example

Two values from key => value pairs are considered equal only if (string) $elem1 === (string) $elem2 . In other words a strict check takes place so the string representations must be the same.

<?php
$array1 
= array(012);
$array2 = array("00""01""2");
$result array_diff_assoc($array1$array2);
print_r($result);
?>

The above example will output:

Array
(
    [0] => 0
    [1] => 1
    )

Notes

Note: This function only checks one dimension of a n-dimensional array. Of course you can check deeper dimensions by using, for example, array_diff_assoc($array1[0], $array2[0]);.

Note: Ensure you pass arguments in the correct order when comparing similar arrays with more keys. The new array should be the first in the list.

See Also

  • array_diff() - Computes the difference of arrays
  • array_diff_uassoc() - Computes the difference of arrays with additional index check which is performed by a user supplied callback function
  • array_udiff_assoc() - Computes the difference of arrays with additional index check, compares data by a callback function
  • array_udiff_uassoc() - Computes the difference of arrays with additional index check, compares data and indexes by a callback function
  • array_intersect() - Computes the intersection of arrays
  • array_intersect_assoc() - Computes the intersection of arrays with additional index check

add a note

User Contributed Notes 20 notes

up
58
Giosh
9 years ago
The array_diff_assoc_array from "chinello at gmail dot com" (and others) will not work for arrays with null values. That's because !isset is true when an array key doesn't exists or is set to null.

(sorry for the changed indent-style)
<?php
function array_diff_assoc_recursive($array1, $array2) {
   
$difference=array();
    foreach(
$array1 as $key => $value) {
        if(
is_array($value) ) {
            if( !isset(
$array2[$key]) || !is_array($array2[$key]) ) {
               
$difference[$key] = $value;
            } else {
               
$new_diff = array_diff_assoc_recursive($value, $array2[$key]);
                if( !empty(
$new_diff) )
                   
$difference[$key] = $new_diff;
            }
        } else if( !
array_key_exists($key,$array2) || $array2[$key] !== $value ) {
           
$difference[$key] = $value;
        }
    }
    return
$difference;
}
?>

And here an example (note index 'b' in the output):
<?php
$a1
=array( 'a' => 0, 'b' => null, 'c' => array( 'd' => null ) );
$a2=array( 'a' => 0, 'b' => null );

var_dump( array_diff_assoc_recursive( $a1, $a2 ) );
var_dump( chinello_array_diff_assoc_recursive( $a1, $a2 ) );
?>
array(1) {
  ["c"]=>
  array(1) {
    ["d"]=>
    NULL
  }
}

array(2) {
  ["b"]=>
  NULL
  ["c"]=>
  array(1) {
    ["d"]=>
    NULL
  }
}
up
6
dev5er6 at gmail dot com
8 years ago
Works more like the original function:

<?php

function array_diff_assoc_recursive ( )
{
   
$args = func_get_args ( );
   
$diff = array ( );
    foreach (
array_shift ( $args ) as $key => $val )
    {
        for (
$i = 0, $j = 0, $tmp = array ( $val ) , $count = count ( $args ); $i < $count; $i++ )
            if (
is_array ( $val ) )
                if ( !isset (
$args[$i][$key] ) || !is_array ( $args[$i][$key] ) || empty( $args[$i][$key] ) )
                   
$j++;
                else
                   
$tmp[] = $args[$i][$key];
            elseif ( !
array_key_exists ( $key, $args[$i] ) || $args[$i][$key] !== $val )
               
$j++;
        if (
is_array ( $val ) )
        {
           
$tmp = call_user_func_array ( __FUNCTION__, $tmp );
            if ( ! empty (
$tmp ) ) $diff[$key] = $tmp;
            elseif (
$j == $count ) $diff[$key] = $val;
        }
        elseif (
$j == $count && $count ) $diff[$key] = $val;
    }

    return
$diff;
}

?>
up
5
telefoontoestel at hotmail dot com
8 years ago
an earlier post for recursive array_diff_assoc failed because isset returned false on an array element containing a null value. I updated the code so it compares null values too.

<?php
function array_diff_assoc_recursive($array1, $array2)
{
    foreach(
$array1 as $key => $value)
    {
        if(
is_array($value))
        {
              if(!isset(
$array2[$key]))
              {
                 
$difference[$key] = $value;
              }
              elseif(!
is_array($array2[$key]))
              {
                 
$difference[$key] = $value;
              }
              else
              {
                 
$new_diff = array_diff_assoc_recursive($value, $array2[$key]);
                  if(
$new_diff != FALSE)
                  {
                       
$difference[$key] = $new_diff;
                  }
              }
          }
          elseif(!
array_key_exists($key, $array2) || $array2[$key] != $value)
          {
             
$difference[$key] = $value;
          }
    }
    return !isset(
$difference) ? 0 : $difference;
}
?>
up
17
Michael Richey
9 years ago
If you're looking for a true array_diff_assoc, comparing arrays to determine the difference between two, finding missing values from both, you can use this along with array_merge.

$a = array('a'=>1,'b'=>2,'c'=>3);
$b = array('a'=>1,'b'=>2,'d'=>4);
print_r(array_diff_assoc($a,$b));
// returns:
array
(
    [c] => 3
)

print_r(array_diff_assoc($b,$a));
// returns
array
(
    [d] => 4
)

print_r(array_merge(array_diff_assoc($a,$b),array_diff_assoc($b,$a)));
// returns
array
(
    [c] => 3
    [d] => 4
)
up
11
contact at pascalopitz dot com
15 years ago
The direction of the arguments does actually make a difference:

<?php
$a
= array(
   
'x' => 'x',
   
'y' => 'y',
   
'z' => 'z',
   
't' => 't',
);

$b = array(
   
'x' => 'x',
   
'y' => 'y',
   
'z' => 'z',
   
't' => 't',
   
'g' => 'g',
);

print_r(array_diff_assoc($a, $b));
print_r(array_diff_assoc($b, $a));
?>

echoes:

Array
(
)
Array
(
    [g] => g
)
up
12
chinello at gmail dot com
15 years ago
The following will recursively do an array_diff_assoc, which will calculate differences on a multi-dimensional level.  This not display any notices if a key don't exist and if error_reporting is set to E_ALL:

<?php
function array_diff_assoc_recursive($array1, $array2)
{
    foreach(
$array1 as $key => $value)
    {
        if(
is_array($value))
        {
              if(!isset(
$array2[$key]))
              {
                 
$difference[$key] = $value;
              }
              elseif(!
is_array($array2[$key]))
              {
                 
$difference[$key] = $value;
              }
              else
              {
                 
$new_diff = array_diff_assoc_recursive($value, $array2[$key]);
                  if(
$new_diff != FALSE)
                  {
                       
$difference[$key] = $new_diff;
                  }
              }
          }
          elseif(!isset(
$array2[$key]) || $array2[$key] != $value)
          {
             
$difference[$key] = $value;
          }
    }
    return !isset(
$difference) ? 0 : $difference;
}
?>

[NOTE BY danbrown AT php DOT net: This is a combination of efforts from previous notes deleted.  Contributors included (Michael Johnson), (jochem AT iamjochem DAWT com), (sc1n AT yahoo DOT com), and (anders DOT carlsson AT mds DOT mdh DOT se).]
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4
tero dot lahtinen at iki dot fi
4 years ago
array_diff_assoc will fail, if a value is something that can not be converted to a string.
up
5
benjamin at moonfactory dot co dot jp
17 years ago
Hi all,
For php versions < 4.3...

<?php
/**
* array_diff_assoc for version < 4.3
**/
if (!function_exists('array_diff_assoc'))
{
    function
array_diff_assoc($a1, $a2)
    {
        foreach(
$a1 as $key => $value)
        {
            if(isset(
$a2[$key]))
            {
                if((string)
$value !== (string) $a2[$key])
                {
                    
$r[$key] = $value;
                }
            }else
            {
               
$r[$key] = $value;
            }
        }
        return
$r ;
    }
}

?>
up
2
jrajpu10 at gmail dot com
13 years ago
array_diff_assoc can also be used to find the duplicates in an array

<?php
$arr
= array('1','2','3','4','3','2','5');
$uniques = array_unique($arr);
// array_diff will not work here, array_diff_assoc works as it takes the key // in account.
$dups = array_diff_assoc($arr, $uniques);

print_r($dups);
?>

Note: The index of the $dups is not in strict sequential order as expected by C programmer.
up
3
carl at thep dot lu dot se
19 years ago
To unset elements in an array if you know the keys but not the values, you can do:

<?php
$a
= array("foo", "bar", "baz", "quux");
$b = array(1, 3); // Elements to get rid of

foreach($b as $e)
  unset(
$a[$e]);
?>

Of course this makes most sense if $b has many elements or is dynamically generated.
up
3
Alexander Podgorny
16 years ago
NOTE: the diff_array also removes all the duplicate values that match to the values in the second array:

<?php
    $array1
= array("a","b","c","a","a");
   
$array2 = array("a");

   
$diff = array_diff($array1,$array2);

   
// yields: array("b","c") the duplicate "a" values are removed
?>
up
1
news_yodpeirs at thoftware dot de
11 years ago
A quite simple (yet not very efficient) way to compare the first level of arrays which have values that are not strings:
array_map('unserialize',array_diff_assoc(array_map('serialize',$arr1),array_map('serialize',$arr2)))
Might be useful for debugging (that's what I use it for).
up
2
cedric at daneel dot net
15 years ago
To diff between n-dimensional array, juste use this :

<?php
function array_diff_values($tab1, $tab2)
    {
   
$result = array();
    foreach(
$tab1 as $values) if(! in_array($values, $tab2)) $result[] = $values;
    return
$result;
    }
?>
up
2
spark dot crz at gmail dot com
4 years ago
Recursive implementation accepting multiple n-level-arrays as parameters:

<?php
function recursiveDiff() {
   
$arrs = func_get_args();
   
$first = array_shift($arrs);
   
$diff = [];

    foreach(
$first as $key => $value) {
       
$values = array_map(function($arr) use($key){
            if (
is_array($arr) && !array_key_exists($key, $arr))
                return
null;

            return
$arr[$key];
        },
$arrs);

        if (
in_array($value, $values))
            continue;

        if (
is_array($value)) {
           
array_unshift($values, $value);
           
$diff[$key] = call_user_func_array(__FUNCTION__, $values);
            continue;
        }

       
$diff[$key] = $first[$key];
    }

    return
$diff;
}
?>

The other attempt was cleaner but didn't work for all cases.
up
0
nekto
21 days ago
PHP associative keys are case-sensitive, key "a" is different from key "A":

<?php
$arr
= ["A" => 666];
var_dump($arr["a"]);
var_dump($arr["A"]);
?>

produces:
NULL
int(666)

And in the same way, array_diff_assoc treats keys case-sensitively, and key "A" is not equal to key "a" and will be diffed:

<?php
// in arrays below value of "a" and "A" are the same, but keys are different
// values of "b" are different
// values of "c" are the same
$compareWhat = ["a" => 666, "b" => 666, "c" => 666, ];
$compareWith = ["A" => 666, "b" => 667, "c" => 666, ];

var_dump(array_diff_assoc($compareWhat, $compareWith));
?>

produces:
array(2) {
["a"]=> int(666)
["b"]=> int(666)
}

And if the order of values in array is different, the order of the result will be different, although essentially the result stays the same:

<?php
// the same as above, but "b" comes before "a" in $compareWhat
$compareWhat = ["b" => 666, "a" => 666, "c" => 666, ];
$compareWith = ["A" => 666, "b" => 667, "c" => 666, ];

var_dump(array_diff_assoc($compareWhat, $compareWith));
?>

produces:
array(2) {
["b"]=> int(666)
["a"]=> int(666)
}
up
0
folurinyinka at gmail dot com
3 months ago
Recursive implementation accepting multiple n-level-arrays as parameters:

```php
function recursiveDiff(...$arrays)
{
    $first = array_shift($arrays);
    $diff = [];

    foreach ($first as $key => $value) {
        $values = array_map(function ($arr) use ($key) {
            if (is_array($arr) && !array_key_exists($key, $arr)) {
                return null;
            }

            return isset($arr[$key]) ? $arr[$key] : null;
        }, $arrs);

        if (in_array($value, $values)) {
            continue;
        }

        if (is_array($value)) {
            array_unshift($values, $value);
            $diff[$key] = call_user_func_array(__FUNCTION__, $values);
            continue;
        }

        $diff[$key] = $first[$key];
    }

    return $diff;
}
```
up
0
angujomondi at gmail dot com
1 year ago
For recursive diff of multiple arrays, exending solution provided by Gosh.

<?php

function array_diff_assoc_recursive(array $array, array ...$arrays)
    {
       
$func  = function($array1, $array2) use (&$func){
           
$difference = [];
            foreach (
$array1 as $key => $value) {
                if (
is_array($value)) {
                    if (!isset(
$array2[$key]) || !is_array($array2[$key])) {
                       
$difference[$key] = $value;
                    } else {
                       
$new_diff = $func($value, $array2[$key]);
                        if (!empty(
$new_diff)) {
                           
$difference[$key] = $new_diff;
                        }
                    }
                } else {
                    if (!
array_key_exists($key, $array2) || $array2[$key] !== $value) {
                       
$difference[$key] = $value;
                    }
                }
            }
            return
$difference;
        };
       
$diffs = $array;
        foreach (
$arrays as $_array) {
           
$diffs = $func($diffs, $_array);
        }
        return
$diffs;
    }

?>
up
1
shadow_games at abv dot bg
8 years ago
there is a functiont that i searched long enough now i have created it so someone else to find it if he need it ;]
<?php
   
function compare_two_object_recursive($object_1, $object_2, $object_1_Identifier = false, $object_2_Identifier = false){
       
$object1 = (array)$object_1;
       
$object2 = (array)$object_2;
       
$object3 = array();

       
$o1i = $object_1_Identifier ? $object_1_Identifier : 1;
       
$o2i = $object_2_Identifier ? $object_2_Identifier : 2;

        foreach(
$object1 as $key => $value){
            if(
is_object($object1[$key])){
               
$object1[$key] = (array)$object1[$key];
               
$object2[$key] = (array)$object2[$key];
               
$object3[$key] = (object)compare_two_object_recursive($object1[$key], $object2[$key], $o1i, $o2i);
            }elseif(
is_array($object1[$key])){
               
$object3[$key] = compare_two_object_recursive($object1[$key], $object2[$key], $o1i, $o2i);
            }else{
                if(
$object1[$key] == $object2[$key]){
                   
$object3[$key]['comparison_status'] = "SAME";
                }else{
                   
$object3[$key]['comparison_status'] = "NOT THE SAME";
                   
$object3[$key][$o1i] = $object1[$key];
                   
$object3[$key][$o2i] = $object2[$key];
                }
            }
        }
        return
$object3;
    }
?>
up
-2
spark dot crz at gmail dot com
4 years ago
Yet another recursive implementation, without if-else hell and with multiple parameters just like the original.

<?php
function recursiveDiff() {
   
$arrs = func_get_args();
   
$diff = call_user_func_array('array_diff_assoc', $arrs);

    foreach(
$diff as $key => $value) {
        if (!
is_array($value))
            continue;

       
$children = array_map(function($arr) use($key){
            return
$arr[$key];
        },
$arrs);

       
$diff[$key] = call_user_func_array(__FUNCTION__, $children);
    }

    return
$diff;
}
up
-5
francois-php at ceonizme dot fr
7 years ago
to chinello at gmail dot com
I've had to use your function but it showed that the use of isset can't differentiate the NULL values from not setted values.

Here's a version that takes care of this subtility.

<?php
function array_diff_assoc_recursive($array1, $array2)
{
   
$difference = NULL;
    foreach(
$array1 as $key => $value)
    {
        if(
is_array($value))
        {
            if(!
array_key_exists($key, $array2))
            {
               
$difference[$key] = $value;
            }
            elseif(!
is_array($array2[$key]))
            {
               
$difference[$key] = $value;
            }
            else
            {
               
$new_diff = array_diff_assoc_recursive($value, $array2[$key]);
                if(
$new_diff != FALSE)
                {
                   
$difference[$key] = $new_diff;
                }
            }
        }
        elseif(!
array_key_exists($key, $array2) || $array2[$key] != $value)
        {
           
$difference[$key] = $value;
        }
    }
    return !isset(
$difference) ? 0 : $difference;
}
?>

Hope that helps
François
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