PHP
// Write solid PHP avoiding type juggling traps, array quirks, and common security pitfalls.
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stars:1,933
forks:367
updated:March 4, 2026
SKILL.mdreadonly
SKILL.md Frontmatter
namePHP
slugphp
version1.0.1
descriptionWrite solid PHP avoiding type juggling traps, array quirks, and common security pitfalls.
metadata[object Object]
Quick Reference
| Topic | File |
|---|---|
| Loose typing, ==, ===, type juggling, strict_types | types.md |
| Associative arrays, iteration, array functions | arrays.md |
| Traits, interfaces, visibility, late static binding | oop.md |
| Encoding, interpolation, heredoc, regex | strings.md |
| Exceptions, error handling, @ operator | errors.md |
| SQL injection, XSS, CSRF, input validation | security.md |
| PHP 8+ features, attributes, named args, match | modern.md |
Critical Rules
==coerces types:"0" == falseis true — always use===for strict comparisonin_array($val, $arr)uses loose comparison — passtrueas third param for strictstrpos()returns 0 for match at start — use=== falsenot!strpos()- Never concatenate SQL — use prepared statements with PDO
htmlspecialchars($s, ENT_QUOTES)all output — prevents XSSisset()returns false for null — usearray_key_exists()to check key existsforeach ($arr as &$val)— unset$valafter loop or last ref persistsstatic::late binding vsself::early binding —staticrespects overrides@suppresses errors — avoid, makes debugging impossible- Catch
Throwablefor bothErrorandException— PHP 7+ declare(strict_types=1)per file — enables strict type checkingstrlen()counts bytes — usemb_strlen()for UTF-8 character count- Objects pass by reference-like handle — clone explicitly with
clone $obj array_merge()reindexes numeric keys — use+operator to preserve keys