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(PHP 4 >= 4.0.1, PHP 5, PHP 7, PHP 8)
array_unique — Removes duplicate values from an array
array_unique(array $array, int $flags = SORT_STRING): array
Takes an input
array
and returns a new array without duplicate values.
Note that keys are preserved. If multiple elements compare equal under the given
flags
, then the key and value of the first equal element will be retained.
Note : Two elements are considered equal if and only if
(string) $elem1 === (string) $elem2i.e. when the string representation is the same, the first element will be used.
array
The input array.
flags
The optional second parameter
flags
may be used to modify the sorting behavior using these values:
Sorting type flags:
SORT_REGULAR
- compare items normally (don't change types)
SORT_NUMERIC
- compare items numerically
SORT_STRING
- compare items as strings
SORT_LOCALE_STRING
- compare items as strings, based on the current locale.
Returns the filtered array.
| Version | Description |
|---|---|
| 7.2.0 |
If
flags
is
SORT_STRING
, formerly
array
has been copied and non-unique elements have been removed (without packing the array afterwards), but now a new array is built by adding the unique elements. This can result in different numeric indexes.
|
Example #1 array_unique() example
<?php
$input = array("a" => "green", "red", "b" => "green", "blue", "red");
$result = array_unique($input);
print_r($result);
?>
The above example will output:
Array
(
[a] => green
[0] => red
[1] => blue
)
Example #2 array_unique() and types
<?php
$input = array(4, "4", "3", 4, 3, "3");
$result = array_unique($input);
var_dump($result);
?>
The above example will output:
array(2) {
[0] => int(4)
[2] => string(1) "3"
}
Note : Note that array_unique() is not intended to work on multi dimensional arrays.
(PHP 4, PHP 5, PHP 7, PHP 8)
array_unshift — Prepend one or more elements to the beginning of an array
array_unshift(array &$array, mixed ...$values): int
array_unshift()
prepends passed elements to the front of the
array
. Note that the list of elements is prepended as a whole, so that the prepended elements stay in the same order. All numerical array keys will be modified to start counting from zero while literal keys won't be changed.
Note :
Resets array's internal pointer to the first element.
array
The input array.
values
The values to prepend.
Returns the new number of elements in the
array
.
| Version | Description |
|---|---|
| 7.3.0 | This function can now be called with only one parameter. Formerly, at least two parameters have been required. |
Example #1 array_unshift() example
<?php
$queue = [
"orange",
"banana"
];
array_unshift($queue, "apple", "raspberry");
var_dump($queue);
?>
The above example will output:
array(4) {
[0] =>
string(5) "apple"
[1] =>
string(9) "raspberry"
[2] =>
string(6) "orange"
[3] =>
string(6) "banana"
}
Example #2 Usage with associative arrays
If one associative array is prepended to another associative array, the prepended array is numerically indexed into the former array.
<?php
$foods = [
'apples' => [
'McIntosh' => 'red',
'Granny Smith' => 'green',
],
'oranges' => [
'Navel' => 'orange',
'Valencia' => 'orange',
],
];
$vegetables = [
'lettuce' => [
'Iceberg' => 'green',
'Butterhead' => 'green',
],
'carrots' => [
'Deep Purple Hybrid' => 'purple',
'Imperator' => 'orange',
],
'cucumber' => [
'Kirby' => 'green',
'Gherkin' => 'green',
],
];
array_unshift($foods, $vegetables);
var_dump($foods);
The above example will output:
array(3) {
[0] =>
array(3) {
'lettuce' =>
array(2) {
'Iceberg' =>
string(5) "green"
'Butterhead' =>
string(5) "green"
}
'carrots' =>
array(2) {
'Deep Purple Hybrid' =>
string(6) "purple"
'Imperator' =>
string(6) "orange"
}
'cucumber' =>
array(2) {
'Kirby' =>
string(5) "green"
'Gherkin' =>
string(5) "green"
}
}
'apples' =>
array(2) {
'McIntosh' =>
string(3) "red"
'Granny Smith' =>
string(5) "green"
}
'oranges' =>
array(2) {
'Navel' =>
string(6) "orange"
'Valencia' =>
string(6) "orange"
}
}
(PHP 4, PHP 5, PHP 7, PHP 8)
array_values — Return all the values of an array
array_values(array $array): array
array_values()
returns all the values from the
array
and indexes the array numerically.
array
The array.
Returns an indexed array of values.
Example #1 array_values() example
<?php
$array = array("size" => "XL", "color" => "gold");
print_r(array_values($array));
?>
The above example will output:
Array
(
[0] => XL
[1] => gold
)
(PHP 4, PHP 5, PHP 7, PHP 8)
array_walk — Apply a user supplied function to every member of an array
array_walk(array|object &$array, callable $callback, mixed $arg = null): bool
Applies the user-defined
callback
function to each element of the
array
array.
array_walk()
is not affected by the internal array pointer of
array
.
array_walk()
will walk through the entire array regardless of pointer position.
array
The input array.
callback
Typically,
callback
takes on two parameters. The
array
parameter's value being the first, and the key/index second.
Note :
If
callbackneeds to be working with the actual values of the array, specify the first parameter ofcallbackas a reference. Then, any changes made to those elements will be made in the original array itself.
Note :
Many internal functions (for example strtolower() ) will throw a warning if more than the expected number of argument are passed in and are not usable directly as a
callback.
Only the values of the
array
may potentially be changed; its structure cannot be altered, i.e., the programmer cannot add, unset or reorder elements. If the callback does not respect this requirement, the behavior of this function is undefined, and unpredictable.
arg
If the optional
arg
parameter is supplied, it will be passed as the third parameter to the
callback
.
Returns
true
.
As of PHP 7.1.0, an
ArgumentCountError
will be thrown if the
callback
function requires more than 2 parameters (the value and key of the array member), or more than 3 parameters if the
arg
is also passed. Previously, in this case an error of level E_WARNING would be generated each time
array_walk()
calls
callback
.
| Version | Description |
|---|---|
| 8.0.0 |
If
callback
expects the second or third parameter to be passed by reference, this function will now emit an
E_WARNING
.
|
Example #1 array_walk() example
<?php
$fruits = array("d" => "lemon", "a" => "orange", "b" => "banana", "c" => "apple");
function test_alter(&$item1, $key, $prefix)
{
$item1 = "$prefix: $item1";
}
function test_print($item2, $key)
{
echo "$key. $item2\n";
}
echo "Before ...:\n";
array_walk($fruits, 'test_print');
array_walk($fruits, 'test_alter', 'fruit');
echo "... and after:\n";
array_walk($fruits, 'test_print');
?>
The above example will output:
Before ...: d. lemon a. orange b. banana c. apple ... and after: d. fruit: lemon a. fruit: orange b. fruit: banana c. fruit: apple
Example #2 array_walk() example using anonymous function
<?php
$elements = ['a', 'b', 'c'];
array_walk($elements, function ($value, $key) {
echo "{$key} => {$value}\n";
});
?>
The above example will output:
0 => a 1 => b 2 => c
(PHP 5, PHP 7, PHP 8)
array_walk_recursive — Apply a user function recursively to every member of an array
array_walk_recursive(array|object &$array, callable $callback, mixed $arg = null): bool
Applies the user-defined
callback
function to each element of the
array
. This function will recurse into deeper arrays.
array
The input array.
callback
Typically,
callback
takes on two parameters. The
array
parameter's value being the first, and the key/index second.
Note :
If
callbackneeds to be working with the actual values of the array, specify the first parameter ofcallbackas a reference. Then, any changes made to those elements will be made in the original array itself.
arg
If the optional
arg
parameter is supplied, it will be passed as the third parameter to the
callback
.
Returns
true
on success or
false
on failure.
Example #1 array_walk_recursive() example
<?php
$sweet = array('a' => 'apple', 'b' => 'banana');
$fruits = array('sweet' => $sweet, 'sour' => 'lemon');
function test_print($item, $key)
{
echo "$key holds $item\n";
}
array_walk_recursive($fruits, 'test_print');
?>
The above example will output:
a holds apple b holds banana sour holds lemon
You may notice that the key '
sweet
' is never displayed. Any key that holds an
array
will not be passed to the function.
(PHP 4, PHP 5, PHP 7, PHP 8)
arsort — Sort an array in descending order and maintain index association
arsort(array &$array, int $flags = SORT_REGULAR): bool
Sorts
array
in place in descending order, such that its keys maintain their correlation with the values they are associated with.
This is used mainly when sorting associative arrays where the actual element order is significant.
Note :
If two members compare as equal, they retain their original order. Prior to PHP 8.0.0, their relative order in the sorted array was undefined.
Note :
Resets array's internal pointer to the first element.
array
The input array.
flags
The optional second parameter
flags
may be used to modify the sorting behavior using these values:
Sorting type flags:
SORT_REGULAR
- compare items normally; the details are described in the comparison operators section
SORT_NUMERIC
- compare items numerically
SORT_STRING
- compare items as strings
SORT_LOCALE_STRING
- compare items as strings, based on the current locale. It uses the locale, which can be changed using
setlocale()
SORT_NATURAL
- compare items as strings using "natural ordering" like
natsort()
SORT_FLAG_CASE
- can be combined (bitwise OR) with
SORT_STRING
or
SORT_NATURAL
to sort strings case-insensitively
Always returns
true
.
Example #1 arsort() example
<?php
$fruits = array("d" => "lemon", "a" => "orange", "b" => "banana", "c" => "apple");
arsort($fruits);
foreach ($fruits as $key => $val) {
echo "$key = $val\n";
}
?>
The above example will output:
a = orange d = lemon b = banana c = apple
The fruits have been sorted in reverse alphabetical order, and the index associated with each element has been maintained.