PHP Array Functions

PHP ships with a large set of built-in functions for working with arrays.

These are the ones you are most likely to reach for:

• array() - Builds a new array
• array_change_key_case() - Converts every key to lowercase or uppercase
• array_chunk() - Breaks an array into smaller arrays, or chunks
• array_column() - Picks out the values of one column from the input array
• array_combine() - Builds an array from two others, one supplying the keys and the other the values
• array_count_values() - Counts how many times each value appears
• array_diff() - Compares arrays and gives back the differences, looking at values only
• array_diff_assoc() - Compares arrays and gives back the differences, looking at both keys and values
• array_diff_key() - Compares arrays and gives back the differences, looking at keys only
• array_fill() - Populates an array with a value you choose
• array_fill_keys() - Populates an array with a value, using the keys you list
• array_filter() - Keeps only the values that a callback function accepts
• array_flip() - Swaps each key with its value
• array_intersect() - Compares arrays and gives back what they have in common, looking at values only
• array_intersect_assoc() - Compares arrays and gives back what they have in common, looking at both keys and values
• array_intersect_key() - Compares arrays and gives back what they have in common, looking at keys only
• array_key_exists() - Tells you whether a given key is in the array
• array_keys() - Gives back all of an array's keys
• array_map() - Passes each value to a function you write and collects the new values it returns
• array_merge() - Combines one or more arrays into a single array
• array_merge_recursive() - Combines one or more arrays into a single array, working recursively
• array_multisort() - Sorts several arrays at once, or a multidimensional array
• array_pad() - Extends an array to a given length, filling the new items with a value you specify
• array_pop() - Takes the last element off the array
• array_product() - Multiplies all the values together
• array_push() - Appends one or more elements at the end
• array_rand() - Picks one or more keys at random
• array_reduce() - Reduces an array to a single value with a function you write
• array_replace() - Overwrites the first array's values with those from the arrays after it
• array_replace_recursive() - Overwrites the first array's values with those from the arrays after it, working recursively
• array_reverse() - Gives back the array with its order reversed
• array_search() - Looks for a value and gives back its key
• array_shift() - Takes the first element off the array and gives it back to you
• array_slice() - Gives back a selected part of an array
• array_splice() - Cuts out chosen elements and can put others in their place
• array_sum() - Adds up all the values
• array_unique() - Drops duplicate values
• array_unshift() - Places one or more elements at the start
• array_values() - Gives back all of an array's values
• array_walk() - Runs a function you write on every element
• array_walk_recursive() - Runs a function you write on every element, working recursively
• arsort() - Sorts an associative array by value, high to low
• asort() - Sorts an associative array by value, low to high
• compact() - Builds an array from variables and their values
• count() - Tells you how many elements an array has
• current() - Gives back the element the internal pointer is on
• end() - Moves the internal pointer to the last element
• extract() - Turns array entries into variables in the current symbol table
• in_array() - Tells you whether a given value is in the array
• key() - Gives back the key at the internal pointer's position
• krsort() - Sorts an associative array by key, high to low
• ksort() - Sorts an associative array by key, low to high
• list() - Assigns values from an array to several variables in one step
• natcasesort() - Sorts with a natural order algorithm, ignoring case
• natsort() - Sorts with a natural order algorithm
• next() - Moves the internal pointer forward one element
• pos() - Another name for current()
• prev() - Moves the internal pointer back one element
• range() - Builds an array from a range of elements
• reset() - Moves the internal pointer to the first element
• rsort() - Sorts an indexed array, high to low
• shuffle() - Puts the elements in random order
• sizeof() - Another name for count()
• sort() - Sorts an indexed array, low to high
• uasort() - Sorts by value with a comparison function you write, keeping each key attached to its value
• uksort() - Sorts by key with a comparison function you write
• usort() - Sorts by value with a comparison function you write