Am 2016-04-16 um 19:39 schrieb Dmitry Boyarintsev: > The problem is with using "unsigned" as an index (rather than zero- vs one- based arrays) > Take a while loop as an example, where index can change multiple times. > Current solution: > while i>=0 do > if cond then dec(i); > dec(i); > end; > Unsigned index solution > while i>=0 do > if cond then if i>0 then dec(i); > if i>0 then dec(i); > end; > Without these checks, unsigned integer would loop over to $FFFFFFFF and will continue.
That looks to my like an very artifical example. I never came over a loop where I (conditionally) decremented the index twice. But of course, if you have such a case, then you can only use signed intergers. But in all the following cases I could used an unsigned integer (when having 1-based arrays): 1.) for i := low(array) to high(array) 2.) repeat or while loops where the index is in- or decremented by a maximum of 1 (which IMO is the case in 99,9% of all such loops). 3.) When storing an array index into a variable for later use. Nevertheless, using unsigned integers was only one aspect of 1-based arrays. The main one for me was, that it is much more intuitive and therefore less error prone. I already often had errors when calculating indices for 0-based arrays. And why was a directive implemented to use 0-based indices even for strings but none for 1-based indices in dynamic arrays? IMO the latter would be much more desired. _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
