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array_diff_assoc

(PHP 4 >= 4.3.0, PHP 5)

array_diff_assocComputes the difference of arrays with additional index check

Description

array array_diff_assoc ( array $array1 , array $array2 [, array $... ] )

Compares array1 against array2 and returns the difference. Unlike array_diff() the array keys are also used in the comparison.

Parameters

array1

The array to compare from

array2

An array to compare against

...

More arrays to compare against

Return Values

Returns an array containing all the values from array1 that are not present in any of the other arrays.

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

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User Contributed Notes 14 notes

up
12
Michael Richey
1 year 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
)
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8
Giosh
1 year 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
  }
}
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6
chinello at gmail dot com
7 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).]
up
6
Alexander Podgorny
8 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
?>
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3
benjamin at moonfactory dot co dot jp
9 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 ;
    }
}

?>
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3
carl at thep dot lu dot se
11 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 $b has many elements or is dynamically generated.
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1
news_yodpeirs at thoftware dot de
3 years ago
A quite simple (yet not very efficient) way to compare the first level of arrays which have values that are not strings:
array_map('unserialize',array_diff_assoc(array_map('serialize',$arr1),array_map('serialize',$arr2)))
Might be useful for debugging (that's what I use it for).
up
1
contact at pascalopitz dot com
7 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
)
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1
cedric at daneel dot net
7 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
0
francois-php at ceonizme dot fr
19 days 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
Fran├žois
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0
shadow_games at abv dot bg
3 months 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;
    }
?>
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0
dev5er6 at gmail dot com
5 months 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
0
telefoontoestel at hotmail dot com
7 months 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
0
jrajpu10 at gmail dot com
5 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.
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