FOR parameters (end value, step) do not upgate

[tsh73]

It just bite me so I thought I could warn you.

If you have variables used in a FOR as end value, step
like
for i =1 to k step h
bevare that changing them in a loop does not change loop execution.
Look:
k=5
print "k before loop", k
for i =1 to k
   if i = 2 then k = 3
   print i,"k inside loop", k
next
print "k after loop", k

result:
k before loop               5
1             k inside loop               5
2             k inside loop               3
3             k inside loop               3
4             k inside loop               3
5             k inside loop               3
k after loop  3

expected (by me) result:
k before loop               5
1             k inside loop               5
2             k inside loop               3
3             k inside loop               3
k after loop  3


Now, I can fix that with EXIT FOR:
k=5
print "k before loop", k
for i =1 to k
   if i>k then exit for
   if i = 2 then k = 3
   print i,"k inside loop", k
next
print "k after loop", k


But for similar change in step variable I do not see a fix (luckily I do not need it)
k=10
h=2
print "k before loop", k
for i =1 to k step h
   if i = 7 then h = 1
   print i,"h inside loop", h
next
print "k after loop", k

result
h before loop               2
1             h inside loop               2
3             h inside loop               2
5             h inside loop               2
7             h inside loop               1
9             h inside loop               1
h after loop  1


(I expect to have line with i = 8 as well)

---

EDIT
I did some jumping through the hoops to run qbasic.exe in Win10 64 bit (: DOSBOX)
and I could confirm QBasic befaves exactly like this.
Just one of cases there you think to know how things work, but indeed you aren't.

[honkytonk]


 k=10: h=2
 for i =1 to k step h
     if i = 7 then h = 2: exit for
 next
 for i =1 to k step h
   print i
 next


[tsh73]

Rather like this
 k=10: h=2
 for i =1 to k step h
   print i, h
   if i = 7 then h = 1: exit for
 next
 for j = i+1 to k step h
   print j, h
 next

But the problem is not that it cannot be done.
Problem is the difference between "how I know it is" and "how it actually is".

[honkytonk]

Always check if "JB" can touch his foot with his tongue;
Because in theory it is possible.