Question

So lets say

start = 10
end = 30

now I need a loop that goes from startto end

I was thinking of something like this:

for i in [start..end]
  print i

but that does not quite work. Is there a clean way to do this?

Answer 1

for i in range(start, end+1):
   print i

will give you the output from 10 to inclusive 30.

NOTE: The reason I added +1 to your end value is because the range() function specifies a half-closed interval. This means the first value is included, but the end value is not.

I.e.,

  range(5, 10)

would give you a list of

  5, 6, 7, 8, 9

but not include 10.

You can also specify the step size for range() and a host of other things, see the documenation.

Finally, if you are using Python 2.x you can also use xrange() in place of range(), though in Python 3.x you will only have range() which is why I used it here.

If you are curious about the differences between range() and xrange() (though it is not really directly relevant to your question) the following two SO questions are a good place to start: What is the difference between range and xrange functions in Python 2.X? and Should you always favor xrange() over range()?