PHP Array Functions

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# PHP Array Functions

## PHP Array Introduction

The array functions allow you to manipulate arrays.

PHP supports both simple and multi-dimensional arrays. There are also specific functions for populating arrays from database queries.

## Installation

The array functions are part of the PHP core. There is no installation needed to use these functions.

## PHP Array Functions

PHP: indicates the earliest version of PHP that supports the function.

Function | Description | PHP
--- | --- | ---
array() | Creates an array | 3
array_change_key_case() | Returns an array with all keys in lowercase or uppercase | 4
array_chunk() | Splits an array into chunks of arrays | 4
array_combine() | Creates an array by using one array for keys and another for its values | 5
array_count_values() | Returns an array with the number of occurrences for each value | 4
array_diff() | Compares array values, and returns the differences | 4
array_diff_assoc() | Compares array keys and values, and returns the differences | 4
array_diff_key() | Compares array keys, and returns the differences | 5
array_diff_uassoc() | Compares array keys and values, with an additional user-made function check, and returns the differences | 5
array_diff_ukey() | Compares array keys, with an additional user-made function check, and returns the differences | 5
array_fill() | Fills an array with values | 4
array_filter() | Filters elements of an array using a user-made function | 4
array_flip() | Exchanges all keys with their associated values in an array | 4
array_intersect() | Compares array values, and returns the matches | 4
array_intersect_assoc() | Compares array keys and values, and returns the matches | 4
array_intersect_key() | Compares array keys, and returns the matches | 5
array_intersect_uassoc() | Compares array keys and values, with an additional user-made function check, and returns the matches | 5
array_intersect_ukey() | Compares array keys, with an additional user-made function check, and returns the matches | 5
array_key_exists() | Checks if the specified key exists in the array | 4
array_keys() | Returns all the keys of an array | 4
array_map() | Sends each value of an array to a user-made function, which returns new values | 4
array_merge() | Merges one or more arrays into one array | 4
array_merge_recursive() | Merges one or more arrays into one array | 4
array_multisort() | Sorts multiple or multi-dimensional arrays | 4
array_pad() | Inserts a specified number of items, with a specified value, to an array | 4
array_pop() | Deletes the last element of an array | 4
array_product() | Calculates the product of the values in an array | 5
array_push() | Inserts one or more elements to the end of an array | 4
array_rand() | Returns one or more random keys from an array | 4
array_reduce() | Returns an array as a string, using a user-defined function | 4
array_reverse() | Returns an array in the reverse order | 4
array_search() | Searches an array for a given value and returns the key | 4
array_shift() | Removes the first element from an array, and returns the value of the removed element | 4
array_slice() | Returns selected parts of an array | 4
array_splice() | Removes and replaces specified elements of an array | 4
array_sum() | Returns the sum of the values in an array | 4
array_udiff() | Compares array values in a user-made function and returns an array | 5
array_udiff_assoc() | Compares array keys, and compares array values in a user-made function, and returns an array | 5
array_udiff_uassoc() | Compares array keys and array values in user-made functions, and returns an array | 5
array_uintersect() | Compares array values in a user-made function and returns an array | 5
array_uintersect_assoc() | Compares array keys, and compares array values in a user-made function, and returns an array | 5
array_uintersect_uassoc() | Compares array keys and array values in user-made functions, and returns an array | 5
array_unique() | Removes duplicate values from an array | 4
array_unshift() | Adds one or more elements to the beginning of an array | 4
array_values() | Returns all the values of an array | 4
array_walk() | Applies a user function to every member of an array | 3
array_walk_recursive() | Applies a user function recursively to every member of an array | 5
arsort() | Sorts an array in reverse order and maintain index association | 3
asort() | Sorts an array and maintain index association | 3
compact() | Create array containing variables and their values | 4
count() | Counts elements in an array, or properties in an object | 3
current() | Returns the current element in an array | 3
each() | Returns the current key and value pair from an array | 3
end() | Sets the internal pointer of an array to its last element | 3
extract() | Imports variables into the current symbol table from an array | 3
in_array() | Checks if a specified value exists in an array | 4
key() | Fetches a key from an array | 3
krsort() | Sorts an array by key in reverse order | 3
ksort() | Sorts an array by key | 3
list() | Assigns variables as if they were an array | 3
natcasesort() | Sorts an array using a case insensitive "natural order" algorithm | 4
natsort() | Sorts an array using a "natural order" algorithm | 4
next() | Advance the internal array pointer of an array | 3
pos() | Alias of current() | 3
prev() | Rewinds the internal array pointer | 3
range() | Creates an array containing a range of elements | 3
reset() | Sets the internal pointer of an array to its first element | 3
rsort() | Sorts an array in reverse order | 3
shuffle() | Shuffles an array | 3
sizeof() | Alias of count() | 3
sort() | Sorts an array | 3
uasort() | Sorts an array with a user-defined function and maintain index association | 3
uksort() | Sorts an array by keys using a user-defined function | 3
usort() | Sorts an array by values using a user-defined function | 3

## PHP Array Constants

PHP: indicates the earliest version of PHP that supports the constant.

Constant | Description | PHP
--- | --- | ---
CASE_LOWER | Used with array_change_key_case() to convert array keys to lower case |
CASE_UPPER | Used with array_change_key_case() to convert array keys to upper case |
SORT_ASC | Used with array_multisort() to sort in ascending order |
SORT_DESC | Used with array_multisort() to sort in descending order |
SORT_REGULAR | Used to compare items normally |
SORT_NUMERIC | Used to compare items numerically |
SORT_STRING | Used to compare items as strings |
SORT_LOCALE_STRING | Used to compare items as strings, based on the current locale | 4
COUNT_NORMAL |  |
COUNT_RECURSIVE |  |
EXTR_OVERWRITE |  |
EXTR_SKIP |  |
EXTR_PREFIX_SAME |  |
EXTR_PREFIX_ALL |  |
EXTR_PREFIX_INVALID |  |
EXTR_PREFIX_IF_EXISTS |  |
EXTR_IF_EXISTS |  |
EXTR_REFS |  |

From http://www.w3schools.com (Copyright Refsnes Data)