PHP array_all Function

last modified March 13, 2025

The PHP array_all function checks if all elements in an array pass a test implemented by a callback function. It's useful for validation.

Basic Definition

The array_all function tests whether all elements satisfy a condition. It returns true if all elements pass the test, false otherwise.

Syntax: array_all(array $array, callable $callback): bool. The callback should return true for passing elements. Empty arrays return true.

Basic array_all Example

This shows simple validation of all array elements being positive numbers.

basic_array_all.php

<?php

declare(strict_types=1);

function array_all(array $array, callable $callback): bool {
    foreach ($array as $element) {
        if (!$callback($element)) {
            return false;
        }
    }
    return true;
}

$numbers = [2, 4, 6, 8];
$allEven = array_all($numbers, fn($n): bool => $n % 2 === 0);

echo $allEven ? 'All even' : 'Not all even';

This checks if all numbers are even. The callback tests each element, and array_all returns true since all elements pass the test.

Validating String Lengths

Check if all strings in an array meet a minimum length requirement.

string_lengths.php

<?php

declare(strict_types=1);

$names = ["Alice", "Bob", "Charlie"];
$allLongEnough = array_all($names, fn($name): bool => strlen($name) >= 3);

echo $allLongEnough ? 'All valid' : 'Some too short';

This verifies all names have at least 3 characters. The callback checks string length, returning true for all elements in this case.

Object Property Validation

Validate that all objects in an array have a property meeting criteria.

object_validation.php

<?php

declare(strict_types=1);

class Product {
    public function __construct(
        public string $name,
        public float $price
    ) {}
}

$products = [
    new Product("Laptop", 999.99),
    new Product("Phone", 699.99),
    new Product("Tablet", 399.99)
];

$allExpensive = array_all($products, fn(Product $p): bool => $p->price > 300);

echo $allExpensive ? 'All expensive' : 'Some cheap';

This checks if all products cost more than 300. The callback examines each object's price property, returning true for this dataset.

Empty Array Behavior

array_all returns true for empty arrays, which can be useful.

empty_array.php

<?php

declare(strict_types=1);

$emptyArray = [];
$result = array_all($emptyArray, fn($x): bool => $x > 10);

echo $result ? 'All pass (vacuous truth)' : 'Some fail';

With no elements to check, array_all returns true. This follows mathematical logic where universal quantification over an empty set is true.

Early Termination

array_all stops checking after first failure for efficiency.

early_termination.php

<?php

declare(strict_types=1);

$numbers = [2, 4, 5, 8];
$allEven = array_all($numbers, function($n): bool {
    echo "Checking $n\n";
    return $n % 2 === 0;
});

echo $allEven ? 'All even' : 'Not all even';

The function stops at the first odd number (5). You'll only see output for 2, 4, and 5, demonstrating the short-circuit behavior.

Best Practices

Clear Callbacks: Use descriptive names for callback logic.
Type Safety: Add type hints for robust validation.
Performance: Place likely failures early in large arrays.
Readability: Consider helper functions for complex checks.

Source

PHP Array Filter Documentation (related functionality)

This tutorial covered the PHP array_all pattern with practical examples showing its usage for array validation scenarios.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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