PHP Switch

switch Statements & PHP 8 match Expressions

The switch statement executes different blocks of code based on matching an expression against multiple potential values. Starting in PHP 8.0, the match expression provides a modern, strictly-typed, expression-returning alternative to switch.

switch vs PHP 8 match Expression

Match Expression Workflow

flowchart TD
    A["Input Subject Value"] --> B["PHP 8 match(value)"]
    B --> C{"Arm 1 (Strict ===)"} -- Match --> D["Return Arm 1 Value"]
    B --> E{"Arm 2 (Strict ===)"} -- Match --> F["Return Arm 2 Value"]
    B --> G{"Default Arm"} -- Match --> H["Return Default Value"]

Practical Code Example

<?php
declare(strict_types=1);

// Modern PHP 8 match expression example
function getHTTPStatusMessage(int $statusCode): string
{
    return match ($statusCode) {
        200, 201 => "Success: Request completed successfully.",
        400 => "Client Error: Bad Request payload.",
        401, 403 => "Security Error: Unauthorized or Forbidden access.",
        404 => "Not Found: Resource does not exist.",
        500, 502, 503 => "Server Error: Internal system failure.",
        default => "Unknown HTTP Response Code ($statusCode)",
    };
}

// Legacy switch statement comparison
$userRole = 'editor';
$permissions = [];

switch ($userRole) {
    case 'admin':
        $permissions[] = 'manage_users';
        // fallthrough intentional
    case 'editor':
        $permissions[] = 'publish_articles';
        $permissions[] = 'edit_content';
        break;
    default:
        $permissions[] = 'read_content';
        break;
}

echo getHTTPStatusMessage(404) . "
";
echo "Editor Permissions: " . implode(", ", $permissions) . "
";

Best Practices

• Prefer match over switch in PHP 8+: match is safer due to strict === type checking and eliminates accidental break; omission bugs.
• Always Provide a default Arm in match: Prevents unexpected UnhandledMatchError exceptions when unexpected input is passed.
• Group Multiple Matching Keys with Commas: Use 200, 201 => ... in match arms to avoid redundant case definitions.

Self-Check Challenge

Refactor a switch statement checking $dayName ('Monday', 'Tuesday', etc.) into a modern PHP 8 match expression returning "Weekday" or "Weekend"!