A complete reference for PHP string functions — searching and replacing, manipulation and formatting, case conversion, padding and trimming, multibyte strings with mb_, hashing and encryption, sprintf and number formatting, and the functions most used in real code.
A complete reference for PHP math functions — basic operations, rounding, trigonometry, logarithms, cryptographically secure random numbers, BCMath for arbitrary precision, GMP for large integers, math constants, and correct financial calculation patterns.
A complete guide to PHP filtering and validation — filter_var and filter_input, all the FILTER_VALIDATE_* filters for email, URL, IP, integer, float, boolean, all the FILTER_SANITIZE_* filters for cleaning input, custom validation with callbacks, and safe form validation patterns.
An in-depth reference for lesser-known PHP array functions — array_multisort, array_walk_recursive, array_fill_keys, array_splice, array_pad, complex multi-criteria sorting, advanced set operations, array_udiff and array_uintersect, compact and extract, and idiomatic data pipeline patterns.
A complete guide to XML in PHP — SimpleXML for fast parsing, DOMDocument for full manipulation, XPath for element queries, XML namespaces, generating XML, parsing RSS/Atom feeds, SOAP integration, XMLReader for large files, and converting between XML and PHP arrays.
A complete guide to image manipulation in PHP with the GD extension — creating and opening images, resizing and cropping, text and image watermarks, format conversion, thumbnail generation, colors and drawing, outputting to the browser and files, and safe image upload patterns.
A complete guide to the Standard PHP Library (SPL) — the SplStack, SplQueue, SplHeap, SplPriorityQueue, SplDoublyLinkedList, SplFixedArray, ArrayObject, ArrayIterator, RecursiveIteratorIterator data structures, and when SPL data structures are better than regular arrays.
A complete guide to ZIP archives in PHP with ZipArchive — creating and extracting archives, adding files and directories recursively, encryption, modifying existing archives, streaming for large files, ZIPs from databases, and common data export patterns.