Arrays · Lesson 4 of 7

Multidimensional Arrays

Represent nested records and collections with arrays inside arrays.

Lesson

An array can contain other arrays to represent rows, groups, or nested data. Access each level deliberately and check whether expected keys exist before reading external data. For complex data that needs behavior or invariants, a class or value object is often clearer than deeply nested arrays. The example reads one field from the first row in a small table. 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 Multidimensional Arrays. 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

PHP

$rows = [
    ['name' => 'Tea', 'price' => 3],
    ['name' => 'Coffee', 'price' => 4],
];
echo $rows[0]['name'], ': $', $rows[0]['price'];

Expected output

Tea: $3

Key points

Represent nested records and collections with arrays inside arrays.
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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