PHP Spread Operator and Argument Unpacking

The spread operator unpacks arrays into function arguments and builds new arrays from existing elements.

What It Does

The spread operator unpacks arrays into function arguments and builds new arrays from existing elements. The following examples distinguish a normal use case, a boundary case and a practical application.

Requirements and Compatibility

PHP 8.x and a local test environment. Apply input validation, correct error handling and the requirements of any optional libraries.

The code focuses on the core concept. Production implementation may also need routes, validation, persistence, authorization or deployment tooling.

Example 1: Basic Behavior

Start with the smallest meaningful working case.

<?php
$numbers = [1, 2];
print_r([0, ...$numbers, 3]);

Example 2: Another Case

Examine the edge case and the observable result.

<?php
function area(int $width, int $height): int { return $width * $height; }
echo area(...[3, 4]);

Practical Example: Putting It to Use

Apply the technique to a small practical task.

<?php
$defaults = ['theme' => 'light'];
print_r([...$defaults, 'theme' => 'dark']); // Later string key overrides

Important Behavior and Edge Cases

String keys and numeric keys have different merge behavior in PHP array unpacking.

Comparison with Related Functions or Approaches

Common Beginner Mistakes

Key Takeaways

• The spread operator unpacks arrays into function arguments and builds new arrays from existing elements.
• String keys and numeric keys have different merge behavior in PHP array unpacking.
• Variadic parameters collect multiple passed arguments.

Before adapting these examples, verify the return values, test the failure paths and confirm that your application meets its security and environment requirements.