Is there a do until in Python

Question

Is there a  do until x            in Python  or a nice way to implement such a looping construct

User · Accepted Answer

There is no do-while loop in Python   This is a similar construct  taken from the link above    while True       do something        if condition            break

User · Answer

There s no prepackaged  do-while   but the general Python way to implement peculiar looping constructs is through generators and other iterators  e g    import itertools  def dowhile predicate     it   itertools repeat None    for   in it      yield     if not predicate    break   so  for example   i 7  j 3 for   in dowhile lambda  i lt j     print i  j   i  1  j- 1   executes one leg  as desired  even though the predicate s already false at the start   It s normally better to encapsulate more of the looping logic into your generator  or other iterator  -- for example  if you often have cases where one variable increases  one decreases  and you need a do while loop comparing them  you could code   def incandec i  j  delta 1     while True      yield i  j     if j  lt   i  break     i  delta  j- delta   which you can use like   for i  j in incandec i 7  j 3     print i  j   It s up to you how much loop-related logic you want to put inside your generator  or other iterator  and how much you want to have outside of it  just like for any other use of a function  class  or other mechanism you can use to refactor code out of your main stream of execution   but  generally speaking  I like to see the generator used in a for loop that has little  ideally none   loop control logic   code related to updating state variables for the next loop leg and or making tests about whether you should be looping again or not

User · Answer

No there isn t  Instead use a while loop such as   while 1      statements      if cond      break

User · Answer

I prefer to use a looping variable  as it tends to read a bit nicer than just  while 1    and no ugly-looking break statement   finished   False while not finished          do something        finished   evaluate end condition

[python] Is there a "do ... until" in Python?

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