05 The dot, and escaping it

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Goal

Match version numbers like v1.0 and v2.5, but not v10 or v2-5.

. is the wildcard: it matches any single character except a newline. Useful — and the most common regex bug, because people use it when they mean a literal full stop.

To match a character that has a special meaning — ., *, +, ?, (, [, \ and friends — escape it with a backslash: \. is a real dot.

Try it

Try /v\d.\d/ first and watch v2-5 sneak through. Then fix it.

Go to the terminal

Hint

An unescaped . matches any character, so v\d.\d would accept v2-5. Escape it: /v\d\.\d/.

Show a solution

/v\d\.\d/

This interactive environment needs JavaScript. Everything you need to read is on this page, and the solution works the same way for real.

Regex

Starting Regex…