Question

Every time I need to use a regex I realize I’ve forgotten everything about them.

I am trying to match all words that have only lowercase alphanumeric characters AND do not have doubled alphanumeric characters AND are also within {10,12} characters long.

Now, to figure out if a character is followed by the same character, I would do (.)\1. To see if a word is within 10 and 12 characters I do {10,12}. To grab only lowercase letters and the digits, I do [0-9a-z].

But how do I link them together?

Cheers!

PS: this will be running on a fairly large NLP xml (100mb+), so I would appreciate it if the regex wasn’t the slowest alternative.

Answer 1

I think this will do what you want: –

/\b(?:([a-z0-9])(?!\1)){10,12}\b/

Explanation: –

\b   // Word boundary
(?:
    ([a-z0-9])  // Match lowercase letters or digit
    (?!\1)      // Not followed by the same digit as before
){10,12}        // 10 to 12 times.
\b   // Word boundary