PHP array_filter Example | array_filter() Function Tutorial

PHP array_filter Example | array_filter() Function Tutorial is today’s topic. It filters the values of an array using a callback function. Iterates over each value in an array passing them to the callback function. If the callback function returns a true value, the current value from an array is returned into the result array. Array keys are preserved.

PHP array_filter Example

The array_filter() function filters the values of the array using the callback function.

The array_filter() function passes each value of an input array to the callback function. If the callback function returns a true value, then the current value from ant input is returned into the result array. Array keys are preserved.

Let’s take an example.

<?php

// app.php

function even($value)
{
  return $value % 2 == 0;
}

$arr = [1, 2, 3, 4, 5];
print_r(array_filter($arr,"even"));

In the above code, we are checking every array item which is even, if it is odd then it will be filtered out from the array, and only even item stays in the array.

The output is following.

We can also write the array_filter() function like following.

<?php

// app.php

$arr = [1, 2, 3, 4, 5];
$output = array_filter($arr, function($value) {
  return $value % 2 == 0;  
});
print_r($output);

The output will be the same as above; we have just written an anonymous function.

<?php

// app.php

$arr = ['a' => 1, 'b' => 2, 'c' => 3, 'd' => 4];
$outputA = array_filter($arr, function($k) {
  return $k == 'b';
}, ARRAY_FILTER_USE_KEY);
print_r($outputA);

<?php

// app.php

$arr = ['a' => 1, 'b' => 2, 'c' => 3, 'd' => 4];

$outputB = array_filter($arr, function($v, $k) {
  return $k == 'b' || $v == 4;
}, ARRAY_FILTER_USE_BOTH);
print_r($outputB);

<?php

// app.php

$data = array('first' => 1, 'second' => 2, 'third' => 3);
$data = array_filter($data, function ($item) use (&$data) {
    echo "Filtering key ", key($data)."\n";
    next($data);
});