I think the example given here using classes is convoluting things too much to demonstrate what this function does.
array_udiff() will walk through array_values($a) and array_values($b) and compare each value by using the passed in callback function.
To put it another way, array_udiff() compares $a[0] to $b[0], $b[1], $b[2], and $b[3] using the provided callback function. If the callback returns zero for any of the comparisons then $a[0] will not be in the returned array from array_udiff(). It then compares $a[1] to $b[0], $b[1], $b[2], and $b[3]. Then, finally, $a[2] to $b[0], $b[1], $b[2], and $b[3].
For example, compare_ids($a[0], $b[0]) === -5 while compare_ids($a[1], $b[1]) === 0. Therefore, $a[1] is not returned from array_udiff() since it is present in $b.
<?
$a = array(
array(
'id' => 10,
'name' => 'John',
'color' => 'red',
),
array(
'id' => 20,
'name' => 'Elise',
'color' => 'blue',
),
array(
'id' => 30,
'name' => 'Mark',
'color' => 'red',
),
);
$b = array(
array(
'id' => 15,
'name' => 'Nancy',
'color' => 'black',
),
array(
'id' => 20,
'name' => 'Elise',
'color' => 'blue',
),
array(
'id' => 30,
'name' => 'Mark',
'color' => 'red',
),
array(
'id' => 40,
'name' => 'John',
'color' => 'orange',
),
);
function compare_ids($a, $b)
{
return ($a['id'] - $b['id']);
}
function compare_names($a, $b)
{
return strcmp($a['name'], $b['name']);
}
$ret = array_udiff($a, $b, 'compare_ids');
var_dump($ret);
$ret = array_udiff($b, $a, 'compare_ids');
var_dump($ret);
$ret = array_udiff($a, $b, 'compare_names');
var_dump($ret);
?>
Which returns the following.
In the first return we see that $b has no entry in it with an id of 10.
<?
array(1) {
[0]=>
array(3) {
["id"]=>
int(10)
["name"]=>
string(4) "John"
["color"]=>
string(3) "red"
}
}
?>
In the second return we see that $a has no entry in it with an id of 15 or 40.
<?
array(2) {
[0]=>
array(3) {
["id"]=>
int(15)
["name"]=>
string(5) "Nancy"
["color"]=>
string(5) "black"
}
[3]=>
array(3) {
["id"]=>
int(40)
["name"]=>
string(4) "John"
["color"]=>
string(6) "orange"
}
}
?>
In third return we see that all names in $a are in $b (even though the entry in $b whose name is 'John' is different, the anonymous function is only comparing names).
<?
array(0) {
}
?>
array_udiff
(PHP 5, PHP 7, PHP 8)
array_udiff — Computa la diferencia entre arrays, usando una llamada de retorno para la comparación de datos
Descripción
Computa la diferencia de los arrays usando una función tipo llamada de retorno para la comparación de datos. Esto difiere de array_diff(), la cual usa una función interna para la comparación de datos.
Parámetros
-
array1 -
El primer array.
-
array2 -
El segundo array
-
value_compare_func -
La función llamada de retorno para la comparación.
La función de comparación debe devolver un entero menor, igual o mayor que cero si el primer argumento se considera que sea respectivamente menor, igual o mayor que el segundo. Observe que antes de PHP 7.0.0 este entero debía estar en el rango de -2147483648 a 2147483647.
Valores devueltos
Devuelve un array que contiene todos los valores de array1
que no están presentes en ninguno de los otros argumentos.
Ejemplos
Ejemplo #1 Ejemplo de array_udiff() usando objetos de stdClass
<?php
// Arrays a comparar
$array1 = array(new stdclass, new stdclass,
new stdclass, new stdclass,
);
$array2 = array(
new stdclass, new stdclass,
);
// Establecer algunas propiedades para cada objeto
$array1[0]->width = 11; $array1[0]->height = 3;
$array1[1]->width = 7; $array1[1]->height = 1;
$array1[2]->width = 2; $array1[2]->height = 9;
$array1[3]->width = 5; $array1[3]->height = 7;
$array2[0]->width = 7; $array2[0]->height = 5;
$array2[1]->width = 9; $array2[1]->height = 2;
function compare_by_area($a, $b) {
$areaA = $a->width * $a->height;
$areaB = $b->width * $b->height;
if ($areaA < $areaB) {
return -1;
} elseif ($areaA > $areaB) {
return 1;
} else {
return 0;
}
}
print_r(array_udiff($array1, $array2, 'compare_by_area'));
?>El resultado del ejemplo sería:
Array
(
[0] => stdClass Object
(
[width] => 11
[height] => 3
)
[1] => stdClass Object
(
[width] => 7
[height] => 1
)
)
Ejemplo #2 Ejemplo de array_udiff() usando objetos de DateTime
<?php
class MyCalendar {
public $free = array();
public $booked = array();
public function __construct($week = 'now') {
$start = new DateTime($week);
$start->modify('Monday this week midnight');
$end = clone $start;
$end->modify('Friday this week midnight');
$interval = new DateInterval('P1D');
foreach (new DatePeriod($start, $interval, $end) as $freeTime) {
$this->free[] = $freeTime;
}
}
public function bookAppointment(DateTime $date, $note) {
$this->booked[] = array('date' => $date->modify('midnight'), 'note' => $note);
}
public function checkAvailability() {
return array_udiff($this->free, $this->booked, array($this, 'customCompare'));
}
public function customCompare($free, $booked) {
if (is_array($free)) $a = $free['date'];
else $a = $free;
if (is_array($booked)) $b = $booked['date'];
else $b = $booked;
if ($a == $b) {
return 0;
} elseif ($a > $b) {
return 1;
} else {
return -1;
}
}
}
// Crear un calendario para citas semanales
$myCalendar = new MyCalendar;
// Anotar varias citas para esta semana
$myCalendar->bookAppointment(new DateTime('Monday this week'), "Cleaning GoogleGuy's apartment.");
$myCalendar->bookAppointment(new DateTime('Wednesday this week'), "Going on a snowboarding trip.");
$myCalendar->bookAppointment(new DateTime('Friday this week'), "Fixing buggy code.");
// Comprobar los días disponibles comparando las fechas de $booked con las de $free
echo "I'm available on the following days this week...\n\n";
foreach ($myCalendar->checkAvailability() as $free) {
echo $free->format('l'), "\n";
}
echo "\n\n";
echo "I'm busy on the following days this week...\n\n";
foreach ($myCalendar->booked as $booked) {
echo $booked['date']->format('l'), ": ", $booked['note'], "\n";
}
?>El resultado del ejemplo sería:
I'm available on the following days this week... Tuesday Thursday I'm busy on the following days this week... Monday: Cleaning GoogleGuy's apartment. Wednesday: Going on a snowboarding trip. Friday: Fixing buggy code.
Notas
Nota: Por favor note que esta función sólo analiza una dimensión de un array n-dimensional. Por supuesto, puede analizar dimensiones más profundas usando
array_udiff($array1[0], $array2[0], "data_compare_func");.
Ver también
- array_diff() - Calcula la diferencia entre arrays
- array_diff_assoc() - Calcula la diferencia entre arrays con un chequeo adicional de índices
- array_diff_uassoc() - Calcula la diferencia entre arrays con un chequeo adicional de índices que se realiza por una función de devolución de llamada suministrada por el usuario
- array_udiff_assoc() - Computa la diferencia entre arrays con una comprobación de indices adicional, compara la información mediante una función de llamada de retorno
- array_udiff_uassoc() - Computa la diferencia entre arrays con una verificación de índices adicional, compara la información y los índices mediante una función de llamada de retorno
- array_intersect() - Calcula la intersección de arrays
- array_intersect_assoc() - Calcula la intersección de arrays con un chequeo adicional de índices
- array_uintersect() - Computa una intersección de arrays, compara la información mediante una función de llamada de retorno
- array_uintersect_assoc() - Calcula la intersección de arrays con una comprobación de índices adicional, compara la información mediante una función de retrollamada
- array_uintersect_uassoc() - Calcula la intersección de arrays con una comprobación de índices adicional, compara la información y los índices mediante funciones de retrollamada por separado
add a note
User Contributed Notes 9 notes
Colin ¶
18 years ago
napcoder ¶
8 years ago
Note that the compare function is used also internally, to order the arrays and choose which element compare against in the next round.
If your compare function is not really comparing (ie. returns 0 if elements are equals, 1 otherwise), you will receive an unexpected result.
grantwparks at gmail dot com ¶
16 years ago
Re: "convoluted"
I think the point being made is that array_udiff() can be used not only for comparisons between homogenous arrays, as in your example (and definitely the most common need), but it can be used to compare heterogeneous arrays, too.
Consider:
<?php
function compr_1($a, $b) {
$aVal = is_array($a) ? $a['last_name'] : $a;
$bVal = is_array($b) ? $b['last_name'] : $b;
return strcasecmp($aVal, $bVal);
}
$aEmployees = array(
array('last_name' => 'Smith',
'first_name' => 'Joe',
'phone' => '555-1000'),
array('last_name' => 'Doe',
'first_name' => 'John',
'phone' => '555-2000'),
array('last_name' => 'Flagg',
'first_name' => 'Randall',
'phone' => '666-1000')
);
$aNames = array('Doe', 'Smith', 'Johnson');
$result = array_udiff($aEmployees, $aNames, "compr_1");
print_r($result);
?>
Allowing me to get the "employee" that's not in the name list:
Array ( [2] => Array ( [last_name] => Flagg [first_name] => Randall [phone] => 666-1000 ) )
Something interesting to note, is that the two arguments to the compare function don't correspond to array1 and array2. That's why there has to be logic in it to handle that either of the arguments might be pointing to the more complex employee array. (Found this out the hard way.)
adam dot jorgensen dot za at gmail dot com ¶
16 years ago
It is not stated, by this function also diffs array1 to itself, removing any duplicate values...
b4301775 at klzlk dot com ¶
13 years ago
Quick example for using array_udiff to do a multi-dimensional diff
Returns values of $arr1 that are not in $arr2
<?php
$arr1 = array( array('Bob', 42), array('Phil', 37), array('Frank', 39) );
$arr2 = array( array('Phil', 37), array('Mark', 45) );
$arr3 = array_udiff($arr1, $arr2, create_function(
'$a,$b',
'return strcmp( implode("", $a), implode("", $b) ); ')
);
print_r($arr3);
?>
Output:
Array
(
[0] => Array
(
[0] => Bob
[1] => 42
)
[2] => Array
(
[0] => Frank
[1] => 39
)
)
1
Hope this helps someone
Jorge Morales (morales2k) ¶
5 years ago
I find it that this is an ideal place to apply the spaceship operator, but it was not used in the examples.
Here is Example#1 using the spaceship operator in the comparison function.
<?php
// Arrays to compare
$array1 = array(new stdclass, new stdclass,
new stdclass, new stdclass,
);
$array2 = array(
new stdclass, new stdclass,
);
// Set some properties for each object
$array1[0]->width = 11; $array1[0]->height = 3;
$array1[1]->width = 7; $array1[1]->height = 1;
$array1[2]->width = 2; $array1[2]->height = 9;
$array1[3]->width = 5; $array1[3]->height = 7;
$array2[0]->width = 7; $array2[0]->height = 5;
$array2[1]->width = 9; $array2[1]->height = 2;
function compare_by_area($a, $b) {
$areaA = $a->width * $a->height;
$areaB = $b->width * $b->height;
return $areaA <=> $areaB;
}
print_r(array_udiff($array1, $array2, 'compare_by_area'));
?>
The output is:
Array
(
[0] => stdClass Object
(
[width] => 11
[height] => 3
)
[1] => stdClass Object
(
[width] => 7
[height] => 1
)
)
I find it is pretty awesome you can substitute all of these lines:
if ($areaA < $areaB) {
return -1;
} elseif ($areaA > $areaB) {
return 1;
} else {
return 0;
}
with just:
return $areaA <=> $areaB;
Neat!
dmhouse at gmail dot com ¶
19 years ago
Very easy way of achieving a case-insensitive version of array_diff (or indeed array_diff_assoc, array_intersect or any of these types of functions which have a similar function that takes a callback function as one of their parameters):
array_udiff($array1, $array2, 'strcasecmp');
This works because strcasecmp() compares two strings case-insensitively, as compared to the array_diff() which compares two strings by using the == operator, which is case-sensitive.
jared ¶
15 years ago
Note that php does the string conversion *before* sending the values to the callback function.
aidan at php dot net ¶
20 years ago
This functionality is now implemented in the PEAR package PHP_Compat.
More information about using this function without upgrading your version of PHP can be found on the below link:
http://pear.php.net/package/PHP_Compat
