I do not know, if you took time to look at the next function in https://github.com/DoctorWkt/acwj/tree/master/01_Scanner , but there is a Putback variable, which seems to imply that the scanner goes back (at most one character). Also having to pass around the result of next, instead of having a current pointer, or at least a current character, makes things more complicated (I feel). Being able to look ahead, without having to consume a character, (I feel) is easier, also for keeping track of the correct line and column number. Note that if Putback is equal to '\n', the Line has already be incremented. Seems that this could lead to errors being reported on the wrong line for terminal symbols at the end of the line.
