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PHP Fundamentals Reference
// variables · arrays · functions · OOP · forms · database
ConceptRarityPurposeKey Syntax
echo / printRareOutput text to browserecho "text";
$variablesRareStore values with $ prefix$name = "PHP";
Data TypesRarestring, int, float, bool, null, arraygettype($var)
String FunctionsRareManipulate stringsstrlen(), strtoupper(), str_replace()
if / else / elseifRareConditional branchingif ($x > 0) { ... }
switch / matchRareMulti-value branchingmatch($val) { 1 => "one" }
for / while / foreachRareLoop over dataforeach($arr as $k => $v)
Indexed ArraysRareList of ordered values$arr = [1, 2, 3];
Associative ArraysRareKey-value pairs$user = ["name" => "Ana"];
Array FunctionsEpicSort, filter, map arraysarray_map(), array_filter()
FunctionsRareReusable code blocksfunction greet($name) { ... }
Arrow FunctionsEpicShort closures (PHP 7.4+)$fn = fn($x) => $x * 2;
Variable ScopeEpicglobal, static, local varsglobal $var; static $count;
Classes & ObjectsEpicOOP blueprint and instanceclass Dog { public $name; }
InheritanceEpicExtend a parent classclass Cat extends Animal
Interfaces & AbstractLegendContracts and partial classesinterface Drawable { ... }
TraitsLegendReusable method bundlesuse Logging;
$_GET / $_POSTRareHandle form data$_POST['email']
Form ValidationRareSanitize & validate inputfilter_var(), htmlspecialchars()
SessionsEpicPersist data across pagessession_start(); $_SESSION
CookiesRareStore data in browsersetcookie("name", "val", time()+3600)
File HandlingEpicRead and write filesfile_get_contents(), fopen()
PDO DatabaseEpicQuery databases safely$pdo->prepare($sql)->execute()
Error HandlingEpictry/catch exceptionstry { } catch (Exception $e) { }
Namespaces & AutoloadLegendOrganize large codebasesnamespace App\Models;