[Tutor] Silly loop question

Alan G alan.gauld at freenet.co.uk
Tue Aug 16 18:26:36 CEST 2005

> changeIndex = None
> al = len(line)
> for i in range(al):

And theres the problem.
Pythonprovides two loops, for is really a *foreach* so if you don't
want to process *each* item - eg by jumping forward - then you really
should use while and manage the index thataway.

You can hack about with the indexin a for but basically its abusing
the intent of a for loop. Beter to explicitly hack about in a while 


while i < len(line):
   if changeIndex and i < changeIndex
      i = changeIndex

   if line[i] == "{":
      nextRightBracket = line.find("}",i)
      #other stuff happens
      changeIndex = nextRightBracket + 1
      i += 1

> read Alan's tutorial again. *grin*

Umm, well the section on branching does refer to the two loops and 
each is most appropriate, so...  :-)

Alan G
Author of the Learn to Program web tutor

More information about the Tutor mailing list