I guess that the suffix u is intended to mark unsigned integers. So, I
would say that the alternatives [fFlL] and [fFlLuU] should be swapped.

Okay.

Furthermore, is it intentional that you do not recognize the '_' digit
separator in floating point numbers that begin with a decimal point?

No. I will fix it.

quoted

+	 /* unary and binary operators */
+	 "|[-+*/<>%&^|=!]?==?|--|\\+\\+|<<?=?|>>?=?|&&|\\|[|]?|->|\\.\\*|!!|::|[?:.][.:]"),

What is the justification that there is still "|&&|\\|[|]?|" instead of
"|&&|\\|\\||" that I suggested (and I think I stressed that the point is
that single-character operators are matched elsewhere) and to which you
said "yes, right"?

Yes. Must have slipped my mind. Sorry.

Also, the part "|<<?=?|>>?=?|" can match <, >, <=, and >=, all of which
are matched by other expressions, so you could reduce it to "|<<=|>>=|",
because that are the only tokens that they must match.

Alright.

So, the final regexes are these, right?: 


	 "[a-zA-Z_][a-zA-Z0-9_]*"
	 /* hexadecimal and binary numbers */
	 "|0[xXbB][0-9a-fA-F_]+[lLuU]*"
	 /* integers and floats */
	 "|[0-9][.]?[0-9_]+([Ee][-+]?[0-9]+)?[fFlLuU]*"
	 /* floating point numbers beginning with decimal point */
	 "|[.][0-9][0-9_]*([Ee][-+]?[0-9]+)?[fFlL]?"
	 /* unary and binary operators */
	 "|[-+*/<>%&^|=!]?==?|--|\\+\\+|<<=|>>=|&&|[||]|->|\\.\\*|!!|::|[?:.][.:]"),


Thanks,
Jaydeep.