PHP compact() Function: Usage and Examples

Builds an associative array from variables named by strings.

What Is compact() in PHP?

Builds an associative array from variables named by strings.

Its syntax is:

compact(array|string $var_name, array|string ...$var_names): array

Parameters:

• $var_name — Accepted as array|string; required argument.
• $var_names — Accepted as array|string ...; required argument.

Return type: array. Undefined variable names generate warnings in modern PHP. Do not pass untrusted names into compact().

Availability: Core PHP.

Example 1: Basic Usage

<?php

$name = "Alex"; $role = "editor"; print_r(compact("name", "role"));

Output:

Array
(
    [name] => Alex
    [role] => editor
)

Undefined variable names generate warnings in modern PHP. Do not pass untrusted names into compact().

Example 2: A Different Input

<?php

$city = "Berlin"; print_r(compact(["city"]));

Output:

Array
(
    [city] => Berlin
)

Undefined variable names generate warnings in modern PHP. Do not pass untrusted names into compact().

Practical Example: Applying It in a Program

<?php

$productName = "Keyboard"; $quantity = 3; $unitPrice = 25; $payload = compact("productName", "quantity", "unitPrice"); print_r($payload);

Output:

Array
(
    [productName] => Keyboard
    [quantity] => 3
    [unitPrice] => 25
)

Undefined variable names generate warnings in modern PHP. Do not pass untrusted names into compact().

Important Behavior and Edge Cases

• Key behavior: Undefined variable names generate warnings in modern PHP. Do not pass untrusted names into compact().
• Environment: Core PHP.

Comparison With Related Functions

Common Beginner Mistakes

Key Takeaways

• Builds an associative array from variables named by strings.
• Undefined variable names generate warnings in modern PHP. Do not pass untrusted names into compact().
• Core PHP.

Summary: Undefined variable names generate warnings in modern PHP. Do not pass untrusted names into compact().