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(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";
?>
(PHP 4 >= 4.0.5, PHP 5, PHP 7, PHP 8)
array_reduce — Iteratively reduce the array to a single value using a callback function
array_reduce(array $array, callable $callback, mixed $initial = null): mixed
array_reduce()
applies iteratively the
callback
function to the elements of the
array
, so as to reduce the array to a single value.
array
The input array.
callback
callback(mixed $carry, mixed $item): mixed
carry
Holds the return value of the previous iteration; in the case of the first iteration it instead holds the value of
initial
.
item
Holds the value of the current iteration.
initial
If the optional
initial
is available, it will be used at the beginning of the process, or as a final result in case the array is empty.
Returns the resulting value.
If the array is empty and
initial
is not passed,
array_reduce()
returns
null
.
| Version | Description |
|---|---|
| 8.0.0 |
If
callback
expects a parameter to be passed by reference, this function will now emit an
E_WARNING
.
|
Example #1 array_reduce() example
<?php
function sum($carry, $item)
{
$carry += $item;
return $carry;
}
function product($carry, $item)
{
$carry *= $item;
return $carry;
}
$a = array(1, 2, 3, 4, 5);
$x = array();
var_dump(array_reduce($a, "sum")); // int(15)
var_dump(array_reduce($a, "product", 10)); // int(1200), because: 10*1*2*3*4*5
var_dump(array_reduce($x, "sum", "No data to reduce")); // string(17) "No data to reduce"
?>
(PHP 5 >= 5.3.0, PHP 7, PHP 8)
array_replace — Replaces elements from passed arrays into the first array
array_replace(array $array, array ...$replacements): array
array_replace()
replaces the values of
array
with values having the same keys in each of the following arrays. If a key from the first array exists in the second array, its value will be replaced by the value from the second array. If the key exists in the second array, and not the first, it will be created in the first array. If a key only exists in the first array, it will be left as is. If several arrays are passed for replacement, they will be processed in order, the later arrays overwriting the previous values.
array_replace() is not recursive : it will replace values in the first array by whatever type is in the second array.
array
The array in which elements are replaced.
replacements
Arrays from which elements will be extracted. Values from later arrays overwrite the previous values.
Returns an array .
Example #1 array_replace() example
<?php
$base = array("orange", "banana", "apple", "raspberry");
$replacements = array(0 => "pineapple", 4 => "cherry");
$replacements2 = array(0 => "grape");
$basket = array_replace($base, $replacements, $replacements2);
print_r($basket);
?>
The above example will output:
Array
(
[0] => grape
[1] => banana
[2] => apple
[3] => raspberry
[4] => cherry
)
(PHP 5 >= 5.3.0, PHP 7, PHP 8)
array_replace_recursive — Replaces elements from passed arrays into the first array recursively
array_replace_recursive(array $array, array ...$replacements): array
array_replace_recursive()
replaces the values of
array
with the same values from all the following arrays. If a key from the first array exists in the second array, its value will be replaced by the value from the second array. If the key exists in the second array, and not the first, it will be created in the first array. If a key only exists in the first array, it will be left as is. If several arrays are passed for replacement, they will be processed in order, the later array overwriting the previous values.
array_replace_recursive() is recursive : it will recurse into arrays and apply the same process to the inner value.
When the value in the first array is scalar, it will be replaced by the value in the second array, may it be scalar or array. When the value in the first array and the second array are both arrays, array_replace_recursive() will replace their respective value recursively.
array
The array in which elements are replaced.
replacements
Arrays from which elements will be extracted.
Returns an array .
Example #1 array_replace_recursive() example
<?php
$base = array('citrus' => array( "orange") , 'berries' => array("blackberry", "raspberry"), );
$replacements = array('citrus' => array('pineapple'), 'berries' => array('blueberry'));
$basket = array_replace_recursive($base, $replacements);
print_r($basket);
$basket = array_replace($base, $replacements);
print_r($basket);
?>
The above example will output:
Array
(
[citrus] => Array
(
[0] => pineapple
)
[berries] => Array
(
[0] => blueberry
[1] => raspberry
)
)
Array
(
[citrus] => Array
(
[0] => pineapple
)
[berries] => Array
(
[0] => blueberry
)
)
Example #2 array_replace_recursive() and recursive behavior
<?php
$base = array('citrus' => array("orange") , 'berries' => array("blackberry", "raspberry"), 'others' => 'banana' );
$replacements = array('citrus' => 'pineapple', 'berries' => array('blueberry'), 'others' => array('litchis'));
$replacements2 = array('citrus' => array('pineapple'), 'berries' => array('blueberry'), 'others' => 'litchis');
$basket = array_replace_recursive($base, $replacements, $replacements2);
print_r($basket);
?>
The above example will output:
Array
(
[citrus] => Array
(
[0] => pineapple
)
[berries] => Array
(
[0] => blueberry
[1] => raspberry
)
[others] => litchis
)
(PHP 4, PHP 5, PHP 7, PHP 8)
array_reverse — Return an array with elements in reverse order
array_reverse(array $array, bool $preserve_keys = false): array
Takes an input
array
and returns a new array with the order of the elements reversed.
array
The input array.
preserve_keys
If set to
true
numeric keys are preserved. Non-numeric keys are not affected by this setting and will always be preserved.
Returns the reversed array.
Example #1 array_reverse() example
<?php
$input = array("php", 4.0, array("green", "red"));
$reversed = array_reverse($input);
$preserved = array_reverse($input, true);
print_r($input);
print_r($reversed);
print_r($preserved);
?>
The above example will output:
Array
(
[0] => php
[1] => 4
[2] => Array
(
[0] => green
[1] => red
)
)
Array
(
[0] => Array
(
[0] => green
[1] => red
)
[1] => 4
[2] => php
)
Array
(
[2] => Array
(
[0] => green
[1] => red
)
[1] => 4
[0] => php
)
(PHP 4 >= 4.0.5, PHP 5, PHP 7, PHP 8)
array_search — Searches the array for a given value and returns the first corresponding key if successful
array_search(mixed $needle, array $haystack, bool $strict = false): int|string|false
Searches for
needle
in
haystack
.
needle
The searched value.
Note :
If
needleis a string, the comparison is done in a case-sensitive manner.
haystack
The array.
strict
If the third parameter
strict
is set to
true
then the
array_search()
function will search for
identical
elements in the
haystack
. This means it will also perform a strict type comparison of the
needle
in the
haystack
, and objects must be the same instance.
Returns the key for
needle
if it is found in the array,
false
otherwise.
If
needle
is found in
haystack
more than once, the first matching key is returned. To return the keys for all matching values, use
array_keys()
with the optional
search_value
parameter instead.
This function may return Boolean
false
, but may also return a non-Boolean value which evaluates to
false
. Please read the section on Booleans for more information. Use the === operator for testing the return value of this function.
Example #1 array_search() example
<?php
$array = array(0 => 'blue', 1 => 'red', 2 => 'green', 3 => 'red');
$key = array_search('green', $array); // $key = 2;
$key = array_search('red', $array); // $key = 1;
?>