array_walk
Description
The array_walk of Array for PHP applies a user supplied function to every member of an array.
Syntax
array_walk( array|object &$array, callable $callback, mixed $arg = null ): bool
Parameters
array
The input array.
callback
Typically, callback takes on two parameters. The array parameter's value being the first, and the key/index second.
NOTE: If callback needs to be working with the actual values of the array, specify the first parameter of callback as a reference. Then, any changes made to those elements will be made in the original array itself.
NOTE: Many internal functions (for example strtolower()) will throw a warning if more than the expected number of argument are passed in and are not usable directly as a callback.
Only the values of the array may potentially be changed; its structure cannot be altered, i.e., the programmer cannot add, unset or reorder elements. If the callback does not respect this requirement, the behavior of this function is undefined, and unpredictable.
arg
If the optional arg parameter is supplied, it will be passed as the third parameter to the callback.
Return
Returns true.
Examples
1 · array callback
<? function callback(&$value, $key) { return $value .= " pie"; } $array = [ "a" => "cherry", "b" => "banana", "c" => "apple", "d" => "lemon" ]; $callback = "callback"; array_walk($array, $callback); print_r($array);
Array ( [a] => cherry pie [b] => banana pie [c] => apple pie [d] => lemon pie )
2 · arg
<? function callback(&$value, $key, $arg) { return $value = "$arg: $value pie"; } $array = [ "a" => "cherry", "b" => "banana", "c" => "apple", "d" => "lemon" ]; $callback = "callback"; $arg = "dessert"; array_walk($array, $callback, $arg); print_r($array);
Array ( [a] => dessert: cherry pie [b] => dessert: banana pie [c] => dessert: apple pie [d] => dessert: lemon pie )
Links
Related
Array
- array
- array_all
- array_any
- array_change_key_case
- array_chunk
- array_column
- array_combine
- array_count_values
- array_diff
- array_diff_assoc
- array_diff_key
- array_diff_uassoc
- array_diff_ukey
- array_fill
- array_fill_keys
- array_filter
- array_find
- array_find_key
- array_flip
- array_intersect
- array_intersect_assoc
- array_intersect_key
- array_intersect_uassoc
- array_intersect_ukey
- array_key_exists
- array_key_first
- array_key_last
- array_keys
- array_map
- array_merge
- array_merge_recursive
- array_multisort
- array_pad
- array_pop
- array_product
- array_push
- array_rand
- array_reduce
- array_replace
- array_replace_recursive
- array_reverse
- array_search
- array_shift
- array_slice
- array_splice
- array_sum
- array_udiff
- array_udiff_assoc
- array_udiff_uassoc
- array_uintersect
- array_uintersect_assoc
- array_uintersect_uassoc
- array_unique
- array_unshift
- array_values
- array_walk_recursive
- arsort
- asort
- compact
- count
- current
- end
- extract
- in_array
- key
- key_exists
- krsort
- ksort
- list
- natcasesort
- natsort
- next
- pos
- prev
- range
- reset
- rsort
- shuffle
- sizeof
- sort
- uasort
- uksort
- usort