Tác dụng của hàm array_filter()
The array_filter() function filters the elements of an array using a callback function.
The following table summarizes the technical details of this function.
| Return Value: | Returns the filtered array. |
|---|---|
| Changelog: | The optional flag parameter was added in PHP 5.6.0 |
| Version: | PHP 4.0.6+ |
Syntax
The basic syntax of the array_filter() function is given with:
array_filter(array, callback, flag);
The following example shows the array_filter() function in action.
Example
Run this code »<?php
// Defining callback function
function even($num){
if($num % 2 == 0){
return true;
}
}
// Sample array
$numbers = array("a"=>1, "b"=>2, "c"=>3, "d"=>4, "e"=>5);
// Filtering numbers array
$result = array_filter($numbers, "even");
print_r($result);
?>Parameters
The array_filter() function accepts the following parameters.
| Parameter | Description |
|---|---|
| array | Required. Specifies the array to filter. |
| callback | Optional. Specifies the name of the callback function. |
| flag |
Optional. Specifies what arguments are sent to callback:
Default is
0 which will pass value as the only argument to callback function. |
More Examples
Here're some more examples showing how array_filter() function actually works:
In following example this function returns all the values from the numbers array whose keys are greater than the character "b" using the flag parameter:
Example
Run this code »<?php
// Sample array
$numbers = array("a"=>1, "b"=>2, "c"=>3, "d"=>4, "e"=>5);
// Filtering numbers array using key
$result = array_filter($numbers, function($key){
return $key > "b";
}, ARRAY_FILTER_USE_KEY);
print_r($result);
?>In the following example this function returns the even values whose keys are greater than "b".
Example
Run this code »<?php
// Sample array
$numbers = array("a"=>1, "b"=>2, "c"=>3, "d"=>4, "e"=>5);
// Filtering numbers array using key and value
$result = array_filter($numbers, function($value, $key){
return $key > "b" && !($value & 1);
}, ARRAY_FILTER_USE_BOTH);
print_r($result);
?>