Regular expression for no more than two repeated letters/digits

Question

I have a requirement to handle a regular expression for no more than two of the same letters/digits in an XSL file.

• no space
• does not support special

Answer 1

For matching the same character repeated 3 or more times consecutively, try:

([a-zA-Z0-9])\1{2,}

Sample matches (tested both here and here): AABBAA (no matches), AABBBAAA (matches BBB and AAA), ABABABABABABABA (no matches), ABCCCCCCCCCC (matches CCCCCCCCCC).