Arrays · Lesson 6 of 7

Array Functions

Transform and inspect arrays with standard functions.

Lesson

Functions such as array_map, array_filter, array_values, and in_array help express common collection operations. Use strict mode for in_array when type coercion is not wanted. A short callback is convenient, but split a complicated transformation into a named function. The example filters a score list and keeps values meeting a threshold. Further guidance Choose list indexes for ordered items and descriptive keys for named fields. Check whether an expected key exists before reading it, and preserve keys when their association matters during sorting or filtering. Use a small fixture to test empty, single-item, and nested data. Practice task: Create a fresh example for Array Functions. Predict the result before running it, then change one input and explain why the result changes. Test a normal case and one boundary or invalid case where it applies. Compare your output with the example and note one rule you would use in a real project.

Code examples

Array Functions

PHP

$scores = [42, 75, 91];
$passing = array_filter($scores, fn (int $score): bool => $score >= 60);
echo implode(', ', $passing);

Expected output

75, 91

Key points

Transform and inspect arrays with standard functions.
Use descriptive keys for records and indexes for ordered lists.
Check keys and bounds before accessing data that may be absent.

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