This is the fourth part in a series of educational regex articles. It show how the combination of nested reference (see: How does this regex find triangular numbers?) to "count" within a...

This question is an educational demonstration of the usage of lookahead, nested reference, and conditionals in a PCRE pattern to match ALL palindromes, including the ones that can't be matched by...

I've written a regex pattern to find Fibonacci numbers (it doesn't matter why, I just did). It works wonderfully as expected (see on ideone.com): String FIBONACCI = "(?x) .{0,2} | (?: (?=(\\2?)...

This is the third part in a series of educational regex articles. It follows How does this regex find triangular numbers? (where nested references is first introduced) and How can we match a^n b^n...

This is the second part of a series of educational regex articles. It shows how lookaheads and nested references can be used to match the non-regular languge anbn. Nested references are first int...

Part of a series of educational regex articles, this is a gentle introduction to the concept of nested references. The first few triangular numbers are: 1 = 1 3 = 1 + 2 6 = 1 + 2 + 3 10 = 1...