How to remove empty values from array in PHP?

Use array_filter($array) without a callback. It removes all falsy values including empty strings, 0, null, and false.

Does array_filter() preserve keys?

Yes, array_filter() preserves original keys. Use array_values(array_filter($arr)) to reindex starting from 0.

What is the difference between array_filter() and array_map()?

array_filter() removes elements based on a condition (may return fewer elements). array_map() transforms elements (always returns same count).

PHP array_filter() Function

Array Function PHP 4.0.6+

The array_filter() function filters elements of an array using a callback function, returning only elements that pass the test.

Syntax

array_filter(
    array $array,
    ?callable $callback = null,
    int $mode = 0
): array

Parameters

Parameter	Type	Description
`$array`	array	The array to filter
`$callback`	callable\|null	The callback function. If null, removes falsy values.
`$mode`	int	ARRAY_FILTER_USE_KEY or ARRAY_FILTER_USE_BOTH

Return Value

Returns a filtered array. Keys are preserved.

Try It Online

<?php
// array_filter() - Filter array elements using a callback
// Returns only elements that pass the test

// Example 1: Remove falsy values (no callback)
$mixed = ["hello", "", 0, null, "world", false, [], "php"];
echo "Original array:\n";
print_r($mixed);

$filtered = array_filter($mixed);
echo "After array_filter (no callback):\n";
print_r($filtered);

// Example 2: Filter even numbers
$numbers = range(1, 10);
echo "Numbers 1-10: [" . implode(", ", $numbers) . "]\n";

$even = array_filter($numbers, fn($n) => $n % 2 === 0);
echo "Even numbers: [" . implode(", ", $even) . "]\n\n";

// Example 3: Filter by condition
$products = [
    ["name" => "Laptop", "price" => 999],
    ["name" => "Mouse", "price" => 25],
    ["name" => "Keyboard", "price" => 75],
    ["name" => "Monitor", "price" => 300],
    ["name" => "Cable", "price" => 10]
];

$expensive = array_filter($products, fn($p) => $p['price'] > 50);
echo "Products over $50:\n";
foreach ($expensive as $p) {
    echo "  - {$p['name']}: \${$p['price']}\n";
}

// Example 4: Filter by key
echo "\nFiltering by key:\n";
$user = [
    "id" => 123,
    "name" => "John",
    "password" => "secret123",
    "email" => "john@test.com"
];

$safe = array_filter(
    $user,
    fn($key) => $key !== 'password',
    ARRAY_FILTER_USE_KEY
);
echo "User data (without password):\n";
print_r($safe);

Output

Click Run to execute your code

More Examples

Remove Empty Values

<?php
$data = ["hello", "", "world", null, 0, false, "php"];

// Without callback - removes all falsy values
$filtered = array_filter($data);
print_r($filtered);
// ["hello", "world", "php"] (indices: 0, 2, 6)
?>

Filter with Callback

<?php
$numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

// Keep only even numbers
$even = array_filter($numbers, fn($n) => $n % 2 === 0);
print_r($even);
// [2, 4, 6, 8, 10]
?>

Filter by Key

<?php
$data = [
    "name" => "John",
    "email" => "[email protected]",
    "password" => "secret",
    "age" => 30
];

// Keep only specific keys
$allowed = ["name", "email", "age"];
$filtered = array_filter(
    $data,
    fn($key) => in_array($key, $allowed),
    ARRAY_FILTER_USE_KEY
);
print_r($filtered);
?>

Note: array_filter() preserves keys. Use array_values() to reindex if needed.

Common Use Cases

Removing empty/null values from arrays
Filtering user input
Selecting items matching criteria
Data validation and cleaning

Related Functions

array_map() - Transform array elements
array_values() - Reindex array
in_array() - Check if value exists

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