range and xrange… which one to use ?

[Humble]

range() and xrange() are syntatically same and both can have 3 arguments where last 2 are optional.

‘range(stop) -> list of integers range(start, stop[, step]) -> list of integers..Return a list containing an arithmetic progression of integers.range(i, j) returns [i, i+1, i+2, …, j-1]; start (!) defaults to 0. When step is given, it specifies the increment (or decrement).
For example, range(4) returns [0, 1, 2, 3]. The end point is omitted! These are exactly the valid indices for a list of 4 elements.’

As said above, range() returns list of output elements..

For ex:

>>> range(1,100,10)
[1, 11, 21, 31, 41, 51, 61, 71, 81, 91]
>>> 

>>> xobj = xrange(1,10)

>>> for x in xobj:
...     print x
... 
1
2
3
4
5
6
7
8
9






where xrange() returns a generator.. the final or output list is not given back immediately as range() do.. 

Now which one to use and when ?

range() can be a preferred way if you want  to iterate over the list multiple times. If you used  xrange() for this action , it has to generate an integer object every time you access an index.

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