PHP Bugs #21 to #30 — Common Mistakes Every PHP Developer Must Know published (opens in new tab)

If you've been following this series — Part 1 (Bugs #1–10) covered type juggling and variable scoping, Part 2 (Bugs #11–20) tackled form handling and session quirks — now Part 3 is where things get genuinely dangerous. Bugs #21 to #30 aren't just annoying syntax mistakes. Some are active security vulnerabilities. A few will crash your server under load. Others silently corrupt data without throwing a single error. Let's go through each one. Bug #21 — strlen() Giving Wrong Count for Multibyte ...