Using PHP extract() Function to Convert Array Keys to Variables

extract() function basic usage

The extract() function converts array key‑value pairs into variables. Its basic syntax is:

<code>extract(array $array, int $flags = EXTR_OVERWRITE, string $prefix = null): int</code>

Here, $array is the source array, $flags controls the extraction behavior, and $prefix adds a prefix to variable names.

$flags parameter usage

The $flags parameter determines how extract() behaves during conversion. Common flag options include:

EXTR_OVERWRITE : Overwrites existing variables with the same name (default).

EXTR_SKIP : Skips conversion when a variable with the same name already exists.

EXTR_PREFIX_SAME : Adds the specified prefix to variables that would conflict.

EXTR_PREFIX_ALL : Adds the prefix to all created variables.

EXTR_PREFIX_INVALID : Prefixes invalid variable names.

EXTR_IF_EXISTS : Only converts variables that already exist.

Example demonstration

Assume an array:

<code>$user = array(
    'name' => 'John',
    'age' => 25,
    'email' => '[email protected]'
);</code>

Calling extract($user); creates the variables $name , $age , and $email with values 'John', 25, and '[email protected]' respectively.

Using a prefix

To add a prefix to generated variable names, specify the $prefix argument, e.g.:

<code>extract($user, EXTR_PREFIX_ALL, 'user_');</code>

This produces $user_name , $user_age , and $user_email .

Precautions

When using extract() , keep in mind:

Variable names must not clash with existing variables unless intentional.

The $flags parameter can prevent unwanted overwrites.

After extraction, perform security checks on the variables to avoid potential risks.

Summary

PHP's extract() function provides a convenient way to turn array keys into variables. By properly using the $flags and $prefix parameters, developers can control the extraction process, avoid naming conflicts, and maintain security.