Language basics

27 steps in 9 sets of PHP.

PHP runs most of the web that is not a framework demo: WordPress, Wikipedia, and a long tail of applications that pay salaries. The language those sites run on today is not the one its reputation remembers — PHP 8 has a JIT, enums, match expressions, named arguments, and a type system that catches real mistakes. The dollar sigil on every variable and the arrow on every method make it a distinctive language under your fingers.

This tour covers modern PHP as a language: variables and interpolation, arrays (the one data structure that is secretly three), closures and arrow functions, classes with promoted constructors, enums, and the null-safety operators that tamed a billion notices. The encore ships complete command-line programs. Every seed opens with the <?php tag real files carry, parses under php -l, and runs start to finish on PHP 8.

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Variables & types

Variables & typesDollar-sign variables and the types PHP infers from their values.
String interpolationDouble quotes splice variables into strings; single quotes leave them alone.
Numbers & castsInteger and float arithmetic, plus the casts that tame loose strings.

Control flow

if and elseifBranching on a value with PHP's one-word elseif and the ternary.
The match expressionPHP 8's answer to switch: strict comparison, a return value, no fallthrough.
foreach loopsOne loop, three shapes: values only, key with value, and by reference.

Arrays

ArraysBuilding, growing, slicing, and sorting PHP's list-shaped arrays.
Associative arraysString keys with =>, plus the operators that handle missing ones.
Array functionsmap, filter, and sum: transforming arrays without writing a loop.

Functions

Functions and defaultsTyped functions whose defaults document the call site.
Closures and arrow functionsTwo ways to close over a variable: terse fn() and explicit use().
Spread and named argumentsModern call sites: pick arguments by name, unpack them from arrays.

Strings & regex

String functionsThe everyday string toolkit: trim, replace, split and join.
Formatting with sprintfprintf-style templates for columns, padding and number bases.
Regex with preg_matchPulling structured fields out of a log line with PCRE.

Classes

Constructor promotionPHP 8 constructors that declare, type and assign properties in one stroke.
InterfacesOne contract, two shapes, one loop that cares about neither.
TraitsSharing behavior across classes without inheritance.

Null & errors

Null coalescingThe three operators that tamed a billion undefined-index notices.
Exceptionstry, catch, finally and a custom exception class of your own.
Backed enumsAn enum whose cases carry string values — and behavior of their own.

Modern touches

GeneratorsFunctions that produce values lazily, one yield at a time.
JSONSerializing to JSON and back with the built-in functions.
Readonly & first-class callablesImmutable properties and the (...) syntax that lifts any callable.

Encore

word_freq.phpA word-frequency report over an inline passage, built from array functions.
grade_report.phpPer-student averages, letter grades, and a class summary table.
link_checker.phpPulls every href out of an HTML string and buckets the link styles.