What’s on the Regex Lookarounds poster
A 4-row table: Syntax · Name · Matches when.
None of these consume characters, so they can stack.
- (?=x) — Lookahead — x follows
- (?!x) — Negative lookahead — x does not follow
- (?<=x) — Lookbehind — x precedes
- (?<!x) — Negative lookbehind — x does not precede
Password rules are the classic use: ^(?=.*\d)(?=.*[a-z]).{8,}$ requires a digit and a letter without consuming either.
Questions about the Regex Lookarounds poster
- What’s on the Regex Lookarounds poster?
- A 4-row table: Syntax · Name · Matches when. None of these consume characters, so they can stack. (?=x) — Lookahead — x follows; (?!x) — Negative lookahead — x does not follow; (?<=x) — Lookbehind — x precedes; (?<!x) — Negative lookbehind — x does not precede. Password rules are the classic use: ^(?=.*\d)(?=.*[a-z]).{8,}$ requires a digit and a letter without consuming either.
- Who is the Regex Lookarounds poster for?
- Regex Lookarounds belongs to the Computing section rather than to a school year, because computing is not something one grade owns. Anyone learning languages can pin it up — a beginner, a student mid-course, or someone revising years later.
- When should you use the Regex Lookarounds poster?
- A lookaround checks a condition and then gives back the characters. That is what zero-width means. A wall chart earns its place by being glanceable from where the work is happening, so Regex Lookarounds belongs on the wall where that computing work actually happens, within glancing distance, rather than filed away.
- What other posters go with Regex Lookarounds?
- REST API Design, Bash Scripting and Error Handling sit alongside Regex Lookarounds in the Computing section. Printed together they make a wall rather than a single sheet, which is how a reference set actually gets used.REST API DesignBash ScriptingError Handling
- Is the Regex Lookarounds poster free to download and print?
- Yes. Regex Lookarounds downloads as a free PDF with no account, no email and no watermark, like everything else in the Computing section. Print as many copies as you like for a home, a classroom, a library or a tutoring group; reselling the file is the only thing the licence rules out.Read the licence
- What size does the Regex Lookarounds poster print at?
- Regex Lookarounds is a vector PDF laid out for US Letter, and prints on A4 with Fit to page — the same file, no separate download. Because every mark on it is drawn rather than photographed, it stays sharp enlarged to A3, A2 or A1 at a copy shop. Colour carries emphasis only, so a greyscale print of Regex Lookarounds loses nothing.Printing guide
Related posters
Charts that sit alongside Regex Lookarounds on the same wall.
Browse every Computing poster, or start from the full catalogue.