Python 知識小結

如何在Python運行環境里查看Python版本?用sys就可以。

>>> import sys
>>> sys.version_info
sys.version_info(major=2, minor=7, micro=16, releaselevel='final', serial=0)

xrange和range的區別?

>>> range(10)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> xrange(10)
xrange(10)

range返回的是一個list,xrange是個object。range直接佔用一片內存。xrange object可以像list一樣使用

r = xrange(10)
>>> r[0]
0
>>> r[1]
1
>>> r[3]
3
>>> dir(r)
['__class__', '__delattr__', '__doc__', '__format__', '__getattribute__', '__getitem__', '__hash__', '__init__', '__iter__', '__len__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__reversed__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__']
>>> len(r)
10

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