Is C a great language, or what? Where else could you write something like a+++++b
Well, you can't meaningfully write it in C, either. The rule for lexical analysis
is that at each point during a straightforward left-to-right scan, the longest possible
token is determined, without regard to whether the resulting sequence of tokens
makes sense. The fragment in the question is therefore interpreted as
a ++ ++ + b
and cannot be parsed as a valid expression.