Re: [Ql-Users] loopy bug
On 06/07/2021 14:13, Wolfgang Lenerz via Ql-Users wrote: Hi Per, an interesting pitfall, thanks for pointing that out. It does seem that Qlib sets the value of the repeat loop control variable to 0 at the start of the loop. Do you know how this fares on plain QDOS, not SMSQE? Regards Wolfgang I dont know if this has been documented anywhere, but Im putting it out here as it caused me some grief. It appears that Q-Liberator zeroes the loop variable on entry to a loop. The following demo, which is acceptable (although perhaps not very elegant) S*BASIC, will not work in the same way once compiled with Qlib. 100 loop = 3 110 cnt = 0 120 PRINT 'Start:'! loop, cnt 130 REPeat loop 140 PRINT loop, cnt 150 cnt = cnt + 1 160 IF cnt >= loop: EXIT loop 170 END REPeat loop 180 PRINT 'End:'! loop, cnt 190 PAUSE: QUIT In the Qlib-compiled version the loop is exited after a single run as the condition cnt >= loop is met immediately, to wit 1 >= 0 The worrying part of this is that while I was figuring out what was wrong, running an embedded routine like this many times, the system crashed due to memory corruption. Whether this was due to the SBASIC or Qlib compiled version I cant say right now. So just beware and keep on progging! NB: This works, though. As long as you start out with loop = 0 100 loop = 0 110 cnt = 3 120 PRINT 'Start:'! loop, cnt 130 REPeat loop 140 PRINT loop, cnt 150 loop = loop + 1 160 IF loop >= cnt: EXIT loop 170 END REPeat loop 180 PRINT 'End:'! loop, cnt 190 PAUSE: QUIT I tested it under Qdos JS and both loops work exactly like in Qlib! Minerva, as one might have guessed, behaves like SBASIC. Clearly the smarter approach (why forbid something when it doesnt matter, and which might even come in handy?) but since its not consistent across the board, its best avoided. Bob, Dilwyn: I only discovered this by chance, due to a spelling mistake. Per ___ QL-Users Mailing List
Re: [Ql-Users] loopy bug
Hi Per, an interesting pitfall, thanks for pointing that out. It does seem that Qlib sets the value of the repeat loop control variable to 0 at the start of the loop. Do you know how this fares on plain QDOS, not SMSQE? Regards Wolfgang > I dont know if this has been documented anywhere, but Im putting it out > here as it caused me some grief. > > It appears that Q-Liberator zeroes the loop variable on entry to a loop. > The following demo, which is acceptable (although perhaps not very > elegant) S*BASIC, will not work in the same way once compiled with Qlib. > > 100 loop = 3 > 110 cnt = 0 > 120 PRINT 'Start:'! loop, cnt > 130 REPeat loop > 140 PRINT loop, cnt > 150 cnt = cnt + 1 > 160 IF cnt >= loop: EXIT loop > 170 END REPeat loop > 180 PRINT 'End:'! loop, cnt > 190 PAUSE: QUIT > > In the Qlib-compiled version the loop is exited after a single run as > the condition cnt >= loop is met immediately, to wit 1 >= 0 > > The worrying part of this is that while I was figuring out what was > wrong, running an embedded routine like this many times, the system > crashed due to memory corruption. Whether this was due to the SBASIC or > Qlib compiled version I cant say right now. So just beware and keep on > progging! > > NB: This works, though. As long as you start out with loop = 0 > > 100 loop = 0 > 110 cnt = 3 > 120 PRINT 'Start:'! loop, cnt > 130 REPeat loop > 140 PRINT loop, cnt > 150 loop = loop + 1 > 160 IF loop >= cnt: EXIT loop > 170 END REPeat loop > 180 PRINT 'End:'! loop, cnt > 190 PAUSE: QUIT > > Per > > ___ > QL-Users Mailing List ___ QL-Users Mailing List
Re: [Ql-Users] loopy bug
I have encountered this before, but, like Bob said, assumed it was just a question of a new type of variable being set up. In other words, I assumed I was doing something wrong and simply avoided whatever was happening. Dilwyn On Tue, 6 Jul 2021, 11:55 Bob Spelten via Ql-Users, < ql-users@lists.q-v-d.com> wrote: > pjwitte via Ql-Users wrote: > > I dont know if this has been documented anywhere, but Im putting it out > > here as it caused me some grief. > > > > It appears that Q-Liberator zeroes the loop variable on entry to a loop. > > The following demo, which is acceptable (although perhaps not very > > elegant) S*BASIC, will not work in the same way once compiled with Qlib. > > > > 100 loop = 3 > > 110 cnt = 0 > > 120 PRINT 'Start:'! loop, cnt > > 130 REPeat loop > > 140 PRINT loop, cnt > > 150 cnt = cnt + 1 > > 160 IF cnt >= loop: EXIT loop > > 170 END REPeat loop > > 180 PRINT 'End:'! loop, cnt > > 190 PAUSE: QUIT > > > > In the Qlib-compiled version the loop is exited after a single run as > > the condition cnt >= loop is met immediately, to wit 1 >= 0 > > > > The worrying part of this is that while I was figuring out what was > > wrong, running an embedded routine like this many times, the system > > crashed due to memory corruption. Whether this was due to the SBASIC or > > Qlib compiled version I cant say right now. So just beware and keep on > > progging! > > > > NB: This works, though. As long as you start out with loop = 0 > > > > 100 loop = 0 > > 110 cnt = 3 > > 120 PRINT 'Start:'! loop, cnt > > 130 REPeat loop > > 140 PRINT loop, cnt > > 150 loop = loop + 1 > > 160 IF loop >= cnt: EXIT loop > > 170 END REPeat loop > > 180 PRINT 'End:'! loop, cnt > > 190 PAUSE: QUIT > > > > Not that I have ever had this problem but when using a REPeat variable > as a value I've always made sure it was only used within the Loop. > > In the Name Table a simple variable is marked differently ($0202) from a > REPeat index ($0602), the question is who is doing it right? > When Qlib encounters the 2nd 'loop' it probably sets up a new zero entry > with the same name. > > In your second example the first 'loop = 0' is most likely not relevant. > > Bob > > > -- > Deze e-mail is gecontroleerd op virussen door AVG. > http://www.avg.com > > ___ > QL-Users Mailing List ___ QL-Users Mailing List
Re: [Ql-Users] loopy bug
pjwitte via Ql-Users wrote: I dont know if this has been documented anywhere, but Im putting it out here as it caused me some grief. It appears that Q-Liberator zeroes the loop variable on entry to a loop. The following demo, which is acceptable (although perhaps not very elegant) S*BASIC, will not work in the same way once compiled with Qlib. 100 loop = 3 110 cnt = 0 120 PRINT 'Start:'! loop, cnt 130 REPeat loop 140 PRINT loop, cnt 150 cnt = cnt + 1 160 IF cnt >= loop: EXIT loop 170 END REPeat loop 180 PRINT 'End:'! loop, cnt 190 PAUSE: QUIT In the Qlib-compiled version the loop is exited after a single run as the condition cnt >= loop is met immediately, to wit 1 >= 0 The worrying part of this is that while I was figuring out what was wrong, running an embedded routine like this many times, the system crashed due to memory corruption. Whether this was due to the SBASIC or Qlib compiled version I cant say right now. So just beware and keep on progging! NB: This works, though. As long as you start out with loop = 0 100 loop = 0 110 cnt = 3 120 PRINT 'Start:'! loop, cnt 130 REPeat loop 140 PRINT loop, cnt 150 loop = loop + 1 160 IF loop >= cnt: EXIT loop 170 END REPeat loop 180 PRINT 'End:'! loop, cnt 190 PAUSE: QUIT Not that I have ever had this problem but when using a REPeat variable as a value I've always made sure it was only used within the Loop. In the Name Table a simple variable is marked differently ($0202) from a REPeat index ($0602), the question is who is doing it right? When Qlib encounters the 2nd 'loop' it probably sets up a new zero entry with the same name. In your second example the first 'loop = 0' is most likely not relevant. Bob -- Deze e-mail is gecontroleerd op virussen door AVG. http://www.avg.com ___ QL-Users Mailing List
[Ql-Users] loopy bug
I dont know if this has been documented anywhere, but Im putting it out here as it caused me some grief. It appears that Q-Liberator zeroes the loop variable on entry to a loop. The following demo, which is acceptable (although perhaps not very elegant) S*BASIC, will not work in the same way once compiled with Qlib. 100 loop = 3 110 cnt = 0 120 PRINT 'Start:'! loop, cnt 130 REPeat loop 140 PRINT loop, cnt 150 cnt = cnt + 1 160 IF cnt >= loop: EXIT loop 170 END REPeat loop 180 PRINT 'End:'! loop, cnt 190 PAUSE: QUIT In the Qlib-compiled version the loop is exited after a single run as the condition cnt >= loop is met immediately, to wit 1 >= 0 The worrying part of this is that while I was figuring out what was wrong, running an embedded routine like this many times, the system crashed due to memory corruption. Whether this was due to the SBASIC or Qlib compiled version I cant say right now. So just beware and keep on progging! NB: This works, though. As long as you start out with loop = 0 100 loop = 0 110 cnt = 3 120 PRINT 'Start:'! loop, cnt 130 REPeat loop 140 PRINT loop, cnt 150 loop = loop + 1 160 IF loop >= cnt: EXIT loop 170 END REPeat loop 180 PRINT 'End:'! loop, cnt 190 PAUSE: QUIT Per ___ QL-Users Mailing List
