PHP Standard Library

PHP's standard functions cover arrays, strings, math, dates, streams, filters, JSON, hashing, and more. SPL supplies iterators, exceptions, data structures, and autoload foundations.

Practical example

<?php
$numbers = [4, 1, 3];
sort($numbers, SORT_NUMERIC);
$when = new DateTimeImmutable('now', new DateTimeZone('UTC'));
$queue = new SplQueue();
$queue->enqueue('lesson');

Read signatures and failure semantics carefully because functions differ between false, null, warnings, and exceptions. Prefer DateTimeImmutable and explicit timezones. Use domain types where raw arrays and functions would scatter invariants.