YouTipPHP array_udiff_assoc() Function
Definition and Usage
The array_udiff_assoc() function compares the values of two or more arrays, and returns the differences. This function compares the values of two or more arrays, and returns an array containing the elements from the first array that are not present in any of the other arrays.
Note: This function uses a user-defined function to compare the values. This function compares the values by their keys and values.
Syntax
array_udiff_assoc(array1, array2, array3..., myfunction)Parameter List
| Parameter | Description |
|---|---|
array1 |
Required. The array to compare from. |
array2 |
Required. An array to compare against. |
array3 |
Optional. An array to compare against. |
myfunction |
Required. A string that calls back the comparison function. The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered respectively less than, equal to, or greater than the second. |
Technical Details
| Return Value: | Returns an array containing the elements from the first array that are not present in any of the other arrays. |
|---|---|
| PHP Version: | PHP 5+ |
More Examples
Example 1
Compare the values of two arrays and return the differences:
Code:
<?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","yellow","b"=>"green");
$result=array_udiff_assoc($a1,$a2,"myfunction");
print_r($result);
?>Output:
Array (
=> green
=> blue
)Explanation: In the example above, you can see that "a" exists in both arrays, so it is not included in the result. "b" and "c" are only in the first array, so they appear in the result.
Example 2
Compare with three arrays:
Code:
<?php
function myfunction($a,$b)
{
if ($a===$b)
{
return 0;
}
return ($a>$b)?1:-1;
}
$a1=array("a"=>"red","b"=>"green","c"=>"blue","d"=>"yellow");
$a2=array("a"=>"red","yellow","b"=>"green");
$a3=array("e"=>"red","f"=>"green","c"=>"blue");
$result=array_udiff_assoc($a1,$a2,$a3,"myfunction");
print_r($result);
?>Output:
Array (
=> yellow
)Explanation: With three arrays, only "d" => "yellow" exists in the first array but not in the second or third arrays.
Notes
- The comparison is done by both key and value, so elements with the same value but different keys are considered different.
- The user-defined comparison function should return an integer:
- 0 if both values are equal
- 1 if the first value is greater
- -1 if the first value is less
- This function is different from
array_diff()andarray_udiff()because it also uses the keys for comparison.
Related Functions
- array_diff() - Computes the difference of arrays
- array_diff_assoc() - Computes the difference of arrays with additional index check
- array_udiff() - Computes the difference of arrays by using a callback function for data comparison
- array_intersect_assoc() - Computes the intersection of arrays with additional index check
- array_udiff_uassoc() - Computes the difference of arrays with additional index check, and compares data and indexes by a callback function
PHP array_udiff_assoc() Function
Definition and Usage
The array_udiff_assoc() function compares the values of two or more arrays, and returns the differences. This function compares the values of two or more arrays, and returns an array containing the elements from the first array that are not present in any of the other arrays.
Note: This function uses a user-defined function to compare the values. This function compares the values by their keys and values.
Syntax
array_udiff_assoc(array1, array2, array3..., myfunction)
Parameter List
| Parameter | Description |
|---|---|
array1 |
Required. The array to compare from. |
array2 |
Required. An array to compare against. |
array3 |
Optional. An array to compare against. |
myfunction |
Required. A string that calls back the comparison function. The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered respectively less than, equal to, or greater than the second. |
Technical Details
| Return Value: | Returns an array containing the elements from the first array that are not present in any of the other arrays. |
|---|---|
| PHP Version: | PHP 5+ |
Examples
Example 1
Compare the values of two arrays and return the differences:
Code:
<?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","yellow","b"=>"green");
$result=array_udiff_assoc($a1,$a2,"myfunction");
print_r($result);
?>Output:
Array
(
=> green
=> blue
)Example 2
Compare with three arrays:
Code:
<?php
function myfunction($a,$b)
{
if ($a===$b)
{
return 0;
}
return ($a>$b)?1:-1;
}
$a1=array("a"=>"red","b"=>"green","c"=>"blue","d"=>"yellow");
$a2=array("a"=>"red","yellow","b"=>"green");
$a3=array("e"=>"red","f"=>"green","c"=>"blue");
$result=array_udiff_assoc($a1,$a2,$a3,"myfunction");
print_r($result);
?>Output:
Array
(
=> yellow
)