http://qs321.pair.com?node_id=1211974


in reply to Re^2: Looking for a regular expression for the following pattern.
in thread Looking for a regular expression for the following pattern.

Next try...

/^(([a-zA-Z0-9]{2,}_)*[a-zA-Z0-9]{2,})$/ && print "$_\n" for "1", "a\n", "aa\n", "a_", "aa", "aa_bb_cc_dd", "a1_11_1c_11", +"aaa", "aa_";

Still matches a trailing newline. It does not match "aa_" on purpose as this is not a sequence of two or more alphanumeric characters separated by underscores which was my claim if not the original question.