PHP apcu_fetch() Function: Usage and Examples

Reads a value from the APCu cache.

What Is apcu_fetch() in PHP?

Reads a value from the APCu cache.

Its syntax is:

apcu_fetch(string|array $key, ?bool &$success = null): mixed

Parameters:

$key — Accepted as string|array; required argument.
$success — Accepted as ?bool &; optional default null.

Return type: mixed. Always use the success flag to distinguish a missing key from a stored false value. Cached data may expire at any time.

Availability: Requires APCu enabled for the current PHP SAPI.

Example 1: Basic Usage

<?php

apcu_store("theme", "dark");
echo apcu_fetch("theme");

Result: Results and availability depend on the current PHP process, system permissions, cache, filesystem or installed locale. Always use the success flag to distinguish a missing key from a stored false value. Cached data may expire at any time.

Example 2: A Different Input

<?php

apcu_store("feature", false);
$value = apcu_fetch("feature", $found);
var_dump($found, $value);

Practical Example: Applying It in a Program

<?php

$cacheKey = "user:preferences";
$preferences = apcu_fetch($cacheKey, $found);
if (!$found) { $preferences = ["theme" => "light"]; apcu_store($cacheKey, $preferences, 60); }
print_r($preferences);

Important Behavior and Edge Cases

Key behavior: Always use the success flag to distinguish a missing key from a stored false value. Cached data may expire at any time.
Environment: Requires APCu enabled for the current PHP SAPI.

Comparison With Related Functions

Function	Purpose
`apcu_fetch()`	reads a value from the APCu cache.
`apcu_store()`	apcu_fetch() reads cached data; apcu_store() writes or replaces it.

Common Beginner Mistakes

Mistake	Correct Approach
Ignoring this behavior: Always use the success flag to distinguish a missing key from a stored false value	Always use the success flag to distinguish a missing key from a stored false value. Cached data may expire at any time.

Key Takeaways

reads a value from the APCu cache.
Always use the success flag to distinguish a missing key from a stored false value. Cached data may expire at any time.
Requires APCu enabled for the current PHP SAPI.

Summary: Always use the success flag to distinguish a missing key from a stored false value. Cached data may expire at any time.