array_reduce
(PHP 4 >= 4.0.5, PHP 5, PHP 7, PHP 8)
array_reduce — Iteratively reduce the array to a single value using a callback function
Description
array_reduce() applies iteratively the
callback function to the elements of the
array, so as to reduce the array to
a single value.
Parameters
-
array -
The input array.
-
callback -
-
carry -
Holds the return value of the previous iteration; in the case of the first iteration it instead holds the value of
initial. -
item -
Holds the value of the current iteration.
-
-
initial -
If the optional
initialis available, it will be used at the beginning of the process, or as a final result in case the array is empty.
Return Values
Returns the resulting value.
If the array is empty and initial is not passed,
array_reduce() returns null.
Changelog
| Version | Description |
|---|---|
| 8.0.0 |
If callback expects a parameter to be passed
by reference, this function will now emit an E_WARNING.
|
Examples
Example #1 array_reduce() example
<?php
function sum($carry, $item)
{
$carry += $item;
return $carry;
}
function product($carry, $item)
{
$carry *= $item;
return $carry;
}
$a = array(1, 2, 3, 4, 5);
$x = array();
var_dump(array_reduce($a, "sum")); // int(15)
var_dump(array_reduce($a, "product", 10)); // int(1200), because: 10*1*2*3*4*5
var_dump(array_reduce($x, "sum", "No data to reduce")); // string(17) "No data to reduce"
?>
See Also
- array_filter() - Filters elements of an array using a callback function
- array_map() - Applies the callback to the elements of the given arrays
- array_unique() - Removes duplicate values from an array
- array_count_values() - Counts all the values of an array
