Why does idcter not reset to 0 when it exceeds maxid?
maxid=9999 idcter=9999 idcter += 1 if(idcter <= maxid) else 0 print('this is good: ' + str(idcter)) idcter += 1 if(idcter <= maxid) else 0 print('now this is weird: ' + str(idcter)) idcter=10000 idcter = idcter + 1 if(idcter <= maxid) else 0 print("that's better: " + str(idcter)) Output:
this is good: 10000 now this is weird: 10000 that's better: 0 So it's a simple fix, but why would idcter not reset after it exceeds maxid?
The operator precedence of
idcter += 1 if (idcter <= maxid) else 0 is visualized by the following grouping
idcter += (1 if (idcter <= maxid) else 0) which means you increment by 0 if the condition doesn't hold.
Compare that to
idcter = idcter + 1 if (idcter <= maxid) else 0 # == idcter = (idcter + 1) if (idcter <= maxid) else 0 Where you assign 0 to the result in the same case.
BTW, 10000 already exceeds your maxid of 9999. One typical way to implement such a resetting increment uses the modulo operator. In your case:
idcter = (idcter+1) % (maxid+1) # 9997 -> 9998 -> 9999 -> 0 -> 1 
+= 0will do the same thing as= 0? If it did, that would make+=very unpredictable and hard to use…idcter += 1 if idcter <= maxid else 0to set the variableidcterto 0. Even if that statement would be parsed as(idcter += 1) if idcter <= maxid else 0, neither of the twoifbranches assigns 0 toidcter. Theidcter += 1branch increments it, and the0branch does nothing. There is no assignment in that branch.