RegexEditor.dev Logo

Regex Editor & Tester

Build, test, and debug regular expressions

← Back to BlogFormal RE›vs Programming Regex
← prevnext →
43 / 44
HelloNo flags — always case-sensitivevs Programming RegexFormal RE✨ Emoji Combos

Programming regex has /i for case-insensitive matching. Formal RE has no flags — the alphabet is fixed and case-sensitive.

✓ Accepts
Hello
✗ Rejects
helloHELLOhElLo
Loading editor…