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PHP / array_chunk — DevDocs

array_chunk

(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)

array_chunk Split an array into chunks

Description

array_chunk(array $array, int $length, bool $preserve_keys = false): array

Chunks an array into arrays with length elements. The last chunk may contain less than length elements.

Parameters

array

The array to work on

length

The size of each chunk

preserve_keys

When set to true keys will be preserved. Default is false which will reindex the chunk numerically

Return Values

Returns a multidimensional numerically indexed array, starting with zero, with each dimension containing length elements.

Errors/Exceptions

If length is less than 1 , a ValueError will be thrown.

Changelog

Version Description
8.0.0 If length is less than 1 , a ValueError will be thrown now; previously, an error of level E_WARNING has been raised instead, and the function returned null .

Examples

Example #1 array_chunk() example

<?php
$input_array = array('a', 'b', 'c', 'd', 'e');
print_r(array_chunk($input_array, 2));
print_r(array_chunk($input_array, 2, true));
?>

The above example will output:

Array
(
    [0] => Array
        (
            [0] => a
            [1] => b
        )

    [1] => Array
        (
            [0] => c
            [1] => d
        )

    [2] => Array
        (
            [0] => e
        )

)
Array
(
    [0] => Array
        (
            [0] => a
            [1] => b
        )

    [1] => Array
        (
            [2] => c
            [3] => d
        )

    [2] => Array
        (
            [4] => e
        )

)

See Also

  • array_slice() - Extract a slice of the array
PHP / array_column — DevDocs

array_column

(PHP 5 >= 5.5.0, PHP 7, PHP 8)

array_column Return the values from a single column in the input array

Description

array_column(array $array, int|string|null $column_key, int|string|null $index_key = null): array

array_column() returns the values from a single column of the array , identified by the column_key . Optionally, an index_key may be provided to index the values in the returned array by the values from the index_key column of the input array.

Parameters

array

A multi-dimensional array or an array of objects from which to pull a column of values from. If an array of objects is provided, then public properties can be directly pulled. In order for protected or private properties to be pulled, the class must implement both the __get() and __isset() magic methods.

column_key

The column of values to return. This value may be an integer key of the column you wish to retrieve, or it may be a string key name for an associative array or property name. It may also be null to return complete arrays or objects (this is useful together with index_key to reindex the array).

index_key

The column to use as the index/keys for the returned array. This value may be the integer key of the column, or it may be the string key name. The value is cast as usual for array keys (however, prior to PHP 8.0.0, objects supporting conversion to string were also allowed).

Return Values

Returns an array of values representing a single column from the input array.

Changelog

Version Description
8.0.0 Objects in columns indicated by index_key parameter will no longer be cast to string and will now throw a TypeError instead.

Examples

Example #1 Get the column of first names from a recordset

<?php
// Array representing a possible record set returned from a database
$records = array(
    array(
        'id' => 2135,
        'first_name' => 'John',
        'last_name' => 'Doe',
    ),
    array(
        'id' => 3245,
        'first_name' => 'Sally',
        'last_name' => 'Smith',
    ),
    array(
        'id' => 5342,
        'first_name' => 'Jane',
        'last_name' => 'Jones',
    ),
    array(
        'id' => 5623,
        'first_name' => 'Peter',
        'last_name' => 'Doe',
    )
);
 
$first_names = array_column($records, 'first_name');
print_r($first_names);
?>

The above example will output:

Array
(
    [0] => John
    [1] => Sally
    [2] => Jane
    [3] => Peter
)

Example #2 Get the column of last names from a recordset, indexed by the "id" column

<?php
// Using the $records array from Example #1
$last_names = array_column($records, 'last_name', 'id');
print_r($last_names);
?>

The above example will output:

Array
(
    [2135] => Doe
    [3245] => Smith
    [5342] => Jones
    [5623] => Doe
)

Example #3 Get the column of usernames from the public "username" property of an object

<?php

class User
{
    public $username;

    public function __construct(string $username)
    {
        $this->username = $username;
    }
}

$users = [
    new User('user 1'),
    new User('user 2'),
    new User('user 3'),
];

print_r(array_column($users, 'username'));
?>

The above example will output:

Array
(
    [0] => user 1
    [1] => user 2
    [2] => user 3
)

Example #4 Get the column of names from the private "name" property of an object using the magic __get() method.

<?php

class Person
{
    private $name;

    public function __construct(string $name)
    {
        $this->name = $name;
    }

    public function __get($prop)
    {
        return $this->$prop;
    }

    public function __isset($prop) : bool
    {
        return isset($this->$prop);
    }
}

$people = [
    new Person('Fred'),
    new Person('Jane'),
    new Person('John'),
];

print_r(array_column($people, 'name'));
?>

The above example will output:

Array
(
    [0] => Fred
    [1] => Jane
    [2] => John
)
If __isset() is not provided, then an empty array will be returned.
Read article
PHP / array_combine — DevDocs

array_combine

(PHP 5, PHP 7, PHP 8)

array_combine Creates an array by using one array for keys and another for its values

Description

array_combine(array $keys, array $values): array

Creates an array by using the values from the keys array as keys and the values from the values array as the corresponding values.

Parameters

keys

Array of keys to be used. Illegal values for key will be converted to string .

values

Array of values to be used

Return Values

Returns the combined array .

Errors/Exceptions

As of PHP 8.0.0, a ValueError is thrown if the number of elements in keys and values does not match. Prior to PHP 8.0.0, a E_WARNING was emitted instead.

Changelog

Version Description
8.0.0 array_combine() will now throw a ValueError if the number of elements for each array is not equal; previously this function returned false instead.

Examples

Example #1 A simple array_combine() example

<?php
$a = array('green', 'red', 'yellow');
$b = array('avocado', 'apple', 'banana');
$c = array_combine($a, $b);

print_r($c);
?>

The above example will output:

Array
(
    [green]  => avocado
    [red]    => apple
    [yellow] => banana
)

See Also

  • array_merge() - Merge one or more arrays
  • array_walk() - Apply a user supplied function to every member of an array
  • array_values() - Return all the values of an array
Read article
PHP / array_count_values — DevDocs

array_count_values

(PHP 4, PHP 5, PHP 7, PHP 8)

array_count_values Counts all the values of an array

Description

array_count_values(array $array): array

array_count_values() returns an array using the values of array (which must be int s or string s) as keys and their frequency in array as values.

Parameters

array

The array of values to count

Return Values

Returns an associative array of values from array as keys and their count as value.

Errors/Exceptions

Throws E_WARNING for every element which is not string or int .

Examples

Example #1 array_count_values() example

<?php
$array = array(1, "hello", 1, "world", "hello");
print_r(array_count_values($array));
?>

The above example will output:

Array
(
    [1] => 2
    [hello] => 2
    [world] => 1
)

See Also

  • count() - Counts all elements in an array or in a Countable object
  • array_unique() - Removes duplicate values from an array
  • array_values() - Return all the values of an array
  • count_chars() - Return information about characters used in a string
Read article
PHP / array_diff — DevDocs

array_diff

(PHP 4 >= 4.0.1, PHP 5, PHP 7, PHP 8)

array_diff Computes the difference of arrays

Description

array_diff(array $array, array ...$arrays): array

Compares array against one or more other arrays and returns the values in array that are not present in any of the other arrays.

Parameters

array

The array to compare from

arrays

Arrays to compare against

Return Values

Returns an array containing all the entries from array that are not present in any of the other arrays. Keys in the array array are preserved.

Changelog

Version Description
8.0.0 This function can now be called with only one parameter. Formerly, at least two parameters have been required.

Examples

Example #1 array_diff() example

<?php
$array1 = array("a" => "green", "red", "blue", "red");
$array2 = array("b" => "green", "yellow", "red");
$result = array_diff($array1, $array2);

print_r($result);
?>

Multiple occurrences in $array1 are all treated the same way. This will output :

Array
(
    [1] => blue
)

Example #2 array_diff() example with non-matching types

Two elements are considered equal if and only if (string) $elem1 === (string) $elem2 . That is, when the string representation is the same.

<?php
// This will generate a Notice that an array cannot be cast to a string.
$source = [1, 2, 3, 4];
$filter = [3, 4, [5], 6];
$result = array_diff($source, $filter);

// Whereas this is fine, since the objects can cast to a string.
class S {
  private $v;

  public function __construct(string $v) {
    $this->v = $v;
  }

  public function __toString() {
    return $this->v;
  }
}

$source = [new S('a'), new S('b'), new S('c')];
$filter = [new S('b'), new S('c'), new S('d')];

$result = array_diff($source, $filter);

// $result now contains one instance of S('a');
?>

To use an alternate comparison function, see array_udiff() .

Notes

Note :

This function only checks one dimension of a n-dimensional array. Of course you can check deeper dimensions by using array_diff($array1[0], $array2[0]); .

See Also

  • 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() - Computes the intersection of arrays
  • array_intersect_assoc() - Computes the intersection of arrays with additional index check
Read article
PHP / array_diff_assoc — DevDocs

array_diff_assoc

(PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)

array_diff_assoc Computes the difference of arrays with additional index check

Description

array_diff_assoc(array $array, array ...$arrays): array

Compares array against arrays and returns the difference. Unlike array_diff() the array keys are also used in the comparison.

Parameters

array

The array to compare from

arrays

Arrays to compare against

Return Values

Returns an array containing all the values from array that are not present in any of the other arrays.

Changelog

Version Description
8.0.0 This function can now be called with only one parameter. Formerly, at least two parameters have been required.

Examples

Example #1 array_diff_assoc() example

In this example you see the "a" => "green" pair is present in both arrays and thus it is not in the output from the function. Unlike this, the pair 0 => "red" is in the output because in the second argument "red" has key which is 1 .

<?php
$array1 = array("a" => "green", "b" => "brown", "c" => "blue", "red");
$array2 = array("a" => "green", "yellow", "red");
$result = array_diff_assoc($array1, $array2);
print_r($result);
?>

The above example will output:

Array
(
    [b] => brown
    [c] => blue
    [0] => red
)

Example #2 array_diff_assoc() example

Two values from key => value pairs are considered equal only if (string) $elem1 === (string) $elem2 . In other words a strict check takes place so the string representations must be the same.

<?php
$array1 = array(0, 1, 2);
$array2 = array("00", "01", "2");
$result = array_diff_assoc($array1, $array2);
print_r($result);
?>

The above example will output:

Array
(
    [0] => 0
    [1] => 1
)

Notes

Note : This function only checks one dimension of a n-dimensional array. Of course you can check deeper dimensions by using, for example, array_diff_assoc($array1[0], $array2[0]); .

Note : Ensure you pass arguments in the correct order when comparing similar arrays with more keys. The new array should be the first in the list.

See Also

  • array_diff() - Computes the difference of arrays
  • array_diff_uassoc() - Computes the difference of arrays with additional index check which is performed by a user supplied callback function
  • array_udiff_assoc() - Computes the difference of arrays with additional index check, compares data by a callback function
  • array_udiff_uassoc() - Computes the difference of arrays with additional index check, compares data and indexes by a callback function
  • array_intersect() - Computes the intersection of arrays
  • array_intersect_assoc() - Computes the intersection of arrays with additional index check
Read article