Array Functions
See Also
See also is_array(), explode(), implode(), split(), preg_split(), and unset().
Table of Contents
- array_change_key_case — Changes the case of all keys in an array
- array_chunk — Split an array into chunks
- array_column — Return the values from a single column in the input array
- array_combine — Creates an array by using one array for keys and another for its values
- array_count_values — Counts all the values of an array
- array_diff_assoc — Computes the difference of arrays with additional index check
- array_diff_key — Computes the difference of arrays using keys for comparison
- array_diff_uassoc — Computes the difference of arrays with additional index check which is performed by a user supplied callback function
- array_diff_ukey — Computes the difference of arrays using a callback function on the keys for comparison
- array_diff — Computes the difference of arrays
- array_fill_keys — Fill an array with values, specifying keys
- array_fill — Fill an array with values
- array_filter — Filters elements of an array using a callback function
- array_flip — Exchanges all keys with their associated values in an array
- array_intersect_assoc — Computes the intersection of arrays with additional index check
- array_intersect_key — Computes the intersection of arrays using keys for comparison
- array_intersect_uassoc — Computes the intersection of arrays with additional index check, compares indexes by a callback function
- array_intersect_ukey — Computes the intersection of arrays using a callback function on the keys for comparison
- array_intersect — Computes the intersection of arrays
- array_key_exists — Checks if the given key or index exists in the array
- array_keys — Return all the keys or a subset of the keys of an array
- array_map — Applies the callback to the elements of the given arrays
- array_merge_recursive — Merge two or more arrays recursively
- array_merge — Merge one or more arrays
- array_multisort — Sort multiple or multi-dimensional arrays
- array_pad — Pad array to the specified length with a value
- array_pop — Pop the element off the end of array
- array_product — Calculate the product of values in an array
- array_push — Push one or more elements onto the end of array
- array_rand — Pick one or more random entries out of an array
- array_reduce — Iteratively reduce the array to a single value using a callback function
- array_replace_recursive — Replaces elements from passed arrays into the first array recursively
- array_replace — Replaces elements from passed arrays into the first array
- array_reverse — Return an array with elements in reverse order
- array_search — Searches the array for a given value and returns the corresponding key if successful
- array_shift — Shift an element off the beginning of array
- array_slice — Extract a slice of the array
- array_splice — Remove a portion of the array and replace it with something else
- array_sum — Calculate the sum of values in an array
- 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_udiff — Computes the difference of arrays by using a callback function for data comparison
- array_uintersect_assoc — Computes the intersection of arrays with additional index check, compares data by a callback function
- array_uintersect_uassoc — Computes the intersection of arrays with additional index check, compares data and indexes by a callback functions
- array_uintersect — Computes the intersection of arrays, compares data by a callback function
- array_unique — Removes duplicate values from an array
- array_unshift — Prepend one or more elements to the beginning of an array
- array_values — Return all the values of an array
- array_walk_recursive — Apply a user function recursively to every member of an array
- array_walk — Apply a user function to every member of an array
- array — Create an array
- arsort — Sort an array in reverse order and maintain index association
- asort — Sort an array and maintain index association
- compact — Create array containing variables and their values
- count — Count all elements in an array, or something in an object
- current — Return the current element in an array
- each — Return the current key and value pair from an array and advance the array cursor
- end — Set the internal pointer of an array to its last element
- extract — Import variables into the current symbol table from an array
- in_array — Checks if a value exists in an array
- key_exists — Alias of array_key_exists
- key — Fetch a key from an array
- krsort — Sort an array by key in reverse order
- ksort — Sort an array by key
- list — Assign variables as if they were an array
- natcasesort — Sort an array using a case insensitive "natural order" algorithm
- natsort — Sort an array using a "natural order" algorithm
- next — Advance the internal array pointer of an array
- pos — Alias of current
- prev — Rewind the internal array pointer
- range — Create an array containing a range of elements
- reset — Set the internal pointer of an array to its first element
- rsort — Sort an array in reverse order
- shuffle — Shuffle an array
- sizeof — Alias of count
- sort — Sort an array
- uasort — Sort an array with a user-defined comparison function and maintain index association
- uksort — Sort an array by keys using a user-defined comparison function
- usort — Sort an array by values using a user-defined comparison function
Коментарии
Big arrays use a lot of memory possibly resulting in memory limit errors. You can reduce memory usage on your script by destroying them as soon as you´re done with them. I was able to get over a few megabytes of memory by simply destroying some variables I didn´t use anymore.You can view the memory usage/gain by using the funcion memory_get_usage(). Hope this helps!
A simple trick that can help you to guess what diff/intersect or sort function does by name.
[suffix] assoc - additional index check. Compares both value and index.
Example: array_diff_assoc, array_intersect_assoc.
[suffix] key - index only check. Ignores value of array, compares only indexes.
Example: array_diff_key, array_intersect_key.
[suffix] **empty** - no "key" or "assoc" word in suffix. Compares values only. Ignores indexes of array.
Example: array_diff, array_intersect.
[prefix] u - will do comparison with user defined function. Letter u can be used twice in some functions (like array_udiff_uassoc), this means that you have to use 2 functions (one for value, one for index).
Example: array_udiff_uassoc, array_uintersect_assoc.
This also works with array sort functions:
[prefix] a - associative. Will preserve keys.
Example: arsort, asort.
[prefix] k - key sort. Will sort array by keys.
Example: uksort, ksort.
[prefix] r - reverse. Will sort array in reverse order.
Example: rsort, krsort.
[prefix] u - sort by user defined function (same as for diff/intersect).
Example: usort, uasort.
I need to take an element from the Array and change its position within the Array by moving the rest of the elements as required.
This is the function that does it. The first parameter is the working Array. The second is the position of the element to move and the third is the position where to move the element.
The function returns the modified Array.
<?php
function array_move_elem($array, $from, $to) {
if ($from == $to) { return $array; }
$c = count($array);
if (($c > $from) and ($c > $to)) {
if ($from < $to) {
$f = $array[$from];
for ($i = $from; $i < $to; $i++) {
$array[$i] = $array[$i+1];
}
$array[$to] = $f;
} else {
$f = $array[$from];
for ($i = $from; $i > $to; $i--) {
$array[$i] = $array[$i-1];
}
$array[$to] = $f;
}
}
return $array;
}
?>
Examples:
<?php
$array = array('Cero','Uno','Dos','Tres','Cuatro','Cinco','Seis','Siete','Ocho','Nueve','Diez');
$array = array_move_elem($array, 3, 5); // Move element in position 3 to position 5...
print_r($array);
$array = array_move_elem($array, 5, 3); // Move element in position 5 to position 3, leaving array as it was... ;)
print_r($array);
?>
Return:
<?php
Array ( [0] => Cero [1] => Uno [2] => Dos [3] => Cuatro [4] => Cinco [5] => Tres [6] => Seis [7] => Siete [8] => Ocho [9] => Nueve [10] => Diez )
Array ( [0] => Cero [1] => Uno [2] => Dos [3] => Tres [4] => Cuatro [5] => Cinco [6] => Seis [7] => Siete [8] => Ocho [9] => Nueve [10] => Diez )
?>
Be careful with type hints in callbacks when using array-traverse functions. In some cases, this may silently cause the data type of elements to change.
<?php
declare(strict_types=1);
// Missing fatal TypeError, No side effects
$unexpected = array_filter(['123', (string) PHP_INT_MAX], fn (int $item) => true);
var_dump($unexpected);
// Missing fatal TypeError, Typecasting side effect
$unexpectedTypecasting = array_map(fn (int $item) => $item, ['123', (string) PHP_INT_MAX]);
var_dump($unexpectedTypecasting);
// Missing fatal TypeError, Typecasting side effect
$unexpectedTypecasting = array_map(fn (string $item) => $item, [123, PHP_INT_MAX]);
var_dump($unexpectedTypecasting);
// Missing fatal TypeError, Typecasting side effect
$unexpectedTypecasting = array_reduce(['123', (string) PHP_INT_MAX], fn (?int $carry, int $item) => $item);
var_dump($unexpectedTypecasting);
$bigIntValue = bcadd((string) PHP_INT_MAX, '1');
// Fatal TypeError
$expectedTypeError = array_map(fn (int $item) => $item, [$bigIntValue]);
var_dump($expectedTypeError);
?>
The above example will output (PHP version 8.3.6, error_reporting E_ALL):
<?php
array(2) {
[0]=>
string(3) "123"
[1]=>
string(19) "9223372036854775807"
}
array(2) {
[0]=>
int(123)
[1]=>
int(9223372036854775807)
}
array(2) {
[0]=>
string(3) "123"
[1]=>
string(19) "9223372036854775807"
}
int(9223372036854775807)
Fatal error: Uncaught TypeError: {closure}(): Argument #1 ($item) must be of type int, string given
?>