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(PHP 4, PHP 5, PHP 7, PHP 8)
array_multisort — Sort multiple or multi-dimensional arrays
array_multisort( array &$array1, mixed $array1_sort_order = SORT_ASC, mixed $array1_sort_flags = SORT_REGULAR, mixed ...$rest ): bool
array_multisort() can be used to sort several arrays at once, or a multi-dimensional array by one or more dimensions.
Associative ( string ) keys will be maintained, but numeric keys will be re-indexed.
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.
array1
An array being sorted.
array1_sort_order
The order used to sort the previous
array
argument. Either
SORT_ASC
to sort ascendingly or
SORT_DESC
to sort descendingly.
This argument can be swapped with
array1_sort_flags
or omitted entirely, in which case
SORT_ASC
is assumed.
array1_sort_flags
Sort options for the previous array argument:
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. 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
This argument can be swapped with
array1_sort_order
or omitted entirely, in which case
SORT_REGULAR
is assumed.
rest
More arrays, optionally followed by sort order and flags. Only elements corresponding to equivalent elements in previous arrays are compared. In other words, the sort is lexicographical.
Returns
true
on success or
false
on failure.
Example #1 Sorting multiple arrays
<?php
$ar1 = array(10, 100, 100, 0);
$ar2 = array(1, 3, 2, 4);
array_multisort($ar1, $ar2);
var_dump($ar1);
var_dump($ar2);
?>
In this example, after sorting, the first array will contain 0, 10, 100, 100. The second array will contain 4, 1, 2, 3. The entries in the second array corresponding to the identical entries in the first array (100 and 100) were sorted as well.
array(4) { [0]=> int(0) [1]=> int(10) [2]=> int(100) [3]=> int(100) } array(4) { [0]=> int(4) [1]=> int(1) [2]=> int(2) [3]=> int(3) }
Example #2 Sorting multi-dimensional array
<?php
$ar = array(
array("10", 11, 100, 100, "a"),
array( 1, 2, "2", 3, 1)
);
array_multisort($ar[0], SORT_ASC, SORT_STRING,
$ar[1], SORT_NUMERIC, SORT_DESC);
var_dump($ar);
?>
In this example, after sorting, the first array will transform to "10", 100, 100, 11, "a" (it was sorted as strings in ascending order). The second will contain 1, 3, "2", 2, 1 (sorted as numbers, in descending order).
array(2) { [0]=> array(5) { [0]=> string(2) "10" [1]=> int(100) [2]=> int(100) [3]=> int(11) [4]=> string(1) "a" } [1]=> array(5) { [0]=> int(1) [1]=> int(3) [2]=> string(1) "2" [3]=> int(2) [4]=> int(1) } }
Example #3 Sorting database results
For this example, each element in the data array represents one row in a table. This type of dataset is typical of database records.
Example data:
volume | edition -------+-------- 67 | 2 86 | 1 85 | 6 98 | 2 86 | 6 67 | 7
The data as an array, called data . This would usually, for example, be obtained by looping with mysqli_fetch_assoc() .
<?php
$data[] = array('volume' => 67, 'edition' => 2);
$data[] = array('volume' => 86, 'edition' => 1);
$data[] = array('volume' => 85, 'edition' => 6);
$data[] = array('volume' => 98, 'edition' => 2);
$data[] = array('volume' => 86, 'edition' => 6);
$data[] = array('volume' => 67, 'edition' => 7);
?>
In this example, we will order by volume descending, edition ascending.
We have an array of rows, but array_multisort() requires an array of columns, so we use the below code to obtain the columns, then perform the sorting.
<?php
// Obtain a list of columns
foreach ($data as $key => $row) {
$volume[$key] = $row['volume'];
$edition[$key] = $row['edition'];
}
// you can use array_column() instead of the above code
$volume = array_column($data, 'volume');
$edition = array_column($data, 'edition');
// Sort the data with volume descending, edition ascending
// Add $data as the last parameter, to sort by the common key
array_multisort($volume, SORT_DESC, $edition, SORT_ASC, $data);
?>
The dataset is now sorted, and will look like this:
volume | edition -------+-------- 98 | 2 86 | 1 86 | 6 85 | 6 67 | 2 67 | 7
Example #4 Case insensitive sorting
Both
SORT_STRING
and
SORT_REGULAR
are case sensitive, strings starting with a capital letter will come before strings starting with a lowercase letter.
To perform a case insensitive sort, force the sorting order to be determined by a lowercase copy of the original array.
<?php
$array = array('Alpha', 'atomic', 'Beta', 'bank');
$array_lowercase = array_map('strtolower', $array);
array_multisort($array_lowercase, SORT_ASC, SORT_STRING, $array);
print_r($array);
?>
The above example will output:
Array ( [0] => Alpha [1] => atomic [2] => bank [3] => Beta )
(PHP 4, PHP 5, PHP 7, PHP 8)
array_pad — Pad array to the specified length with a value
array_pad(array $array, int $length, mixed $value): array
array_pad()
returns a copy of the
array
padded to size specified by
length
with value
value
. If
length
is positive then the array is padded on the right, if it's negative then on the left. If the absolute value of
length
is less than or equal to the length of the
array
then no padding takes place. It is possible to add at most 1048576 elements at a time.
array
Initial array of values to pad.
length
New size of the array.
value
Value to pad if
array
is less than
length
.
Returns a copy of the
array
padded to size specified by
length
with value
value
. If
length
is positive then the array is padded on the right, if it's negative then on the left. If the absolute value of
length
is less than or equal to the length of the
array
then no padding takes place.
Example #1 array_pad() example
<?php
$input = array(12, 10, 9);
$result = array_pad($input, 5, 0);
// result is array(12, 10, 9, 0, 0)
$result = array_pad($input, -7, -1);
// result is array(-1, -1, -1, -1, 12, 10, 9)
$result = array_pad($input, 2, "noop");
// not padded
?>
(PHP 4, PHP 5, PHP 7, PHP 8)
array_pop — Pop the element off the end of array
array_pop(array &$array): mixed
array_pop()
pops and returns the value of the last element of
array
, shortening the
array
by one element.
Note : This function will reset() the array pointer of the input array after use.
array
The array to get the value from.
Returns the value of the last element of
array
. If
array
is empty,
null
will be returned.
Example #1 array_pop() example
<?php
$stack = array("orange", "banana", "apple", "raspberry");
$fruit = array_pop($stack);
print_r($stack);
?>
After this, $stack will have only 3 elements:
Array ( [0] => orange [1] => banana [2] => apple )
and
raspberry
will be assigned to
$fruit
.
(PHP 5 >= 5.1.0, PHP 7, PHP 8)
array_product — Calculate the product of values in an array
array_product(array $array): int|float
array_product() returns the product of values in an array.
array
The array.
Returns the product as an integer or float.
Example #1 array_product() examples
<?php
$a = array(2, 4, 6, 8);
echo "product(a) = " . array_product($a) . "\n";
echo "product(array()) = " . array_product(array()) . "\n";
?>
The above example will output:
product(a) = 384 product(array()) = 1
(PHP 4, PHP 5, PHP 7, PHP 8)
array_push — Push one or more elements onto the end of array
array_push(array &$array, mixed ...$values): int
array_push()
treats
array
as a stack, and pushes the passed variables onto the end of
array
. The length of
array
increases by the number of variables pushed. Has the same effect as:
<?php
$array[] = $var;
?>
Note : If you use array_push() to add one element to the array, it's better to use
$array[] =
because in that way there is no overhead of calling a function.
Note : array_push() will raise a warning if the first argument is not an array. This differed from the
$var[]
behaviour where a new array was created, prior to PHP 7.1.0.
array
The input array.
values
The values to push onto the end of the
array
.
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_push() example
<?php
$stack = array("orange", "banana");
array_push($stack, "apple", "raspberry");
print_r($stack);
?>
The above example will output:
Array ( [0] => orange [1] => banana [2] => apple [3] => raspberry )
(PHP 4, PHP 5, PHP 7, PHP 8)
array_rand — Pick one or more random keys out of an array
array_rand(array $array, int $num = 1): int|string|array
Picks one or more random entries out of an array, and returns the key (or keys) of the random entries.
This function does not generate cryptographically secure values, and must not be used for cryptographic purposes, or purposes that require returned values to be unguessable.
If cryptographically secure randomness is required, the Random\Randomizer may be used with the Random\Engine\Secure engine. For simple use cases, the random_int() and random_bytes() functions provide a convenient and secure API that is backed by the operating system’s CSPRNG .
array
The input array.
num
Specifies how many entries should be picked.
When picking only one entry,
array_rand()
returns the key for a random entry. Otherwise, an array of keys for the random entries is returned. This is done so that random keys can be picked from the array as well as random values. If multiple keys are returned, they will be returned in the order they were present in the original array. Trying to pick more elements than there are in the array will result in an
E_WARNING
level error, and NULL will be returned.
Version | Description |
---|---|
7.1.0 | The internal randomization algorithm has been changed to use the » Mersenne Twister Random Number Generator instead of the libc rand function. |
Example #1 array_rand() example
<?php
$input = array("Neo", "Morpheus", "Trinity", "Cypher", "Tank");
$rand_keys = array_rand($input, 2);
echo $input[$rand_keys[0]] . "\n";
echo $input[$rand_keys[1]] . "\n";
?>