The Longest Match Rule

• Q: what do the following java expressions mean?
  Are they valid?
  (x +++ y), (x + ++ y), (x ++++ y)
• Solution: The scanner matches at each step the longest possible token.
  
  • The first is (x ++ + y), add then increment x.
  • The second is (x + ++ y), increment y then add.
  • The third is (x ++ ++ y), which is invalid.