Python的 for 循环

for 循环

 

与其它大多数语言一样，Python 也拥有 for 循环。你到现在还未曾看到它们的唯一原因就是，Python 在其它太多的方面表现出色，通常你不需要它们。

>>> li = ['a', 'b', 'e']
>>> for s in li:         
...     print s          
a
b
e
>>> print "\n".join(li)  
a
b
e

 

>>> for i in range(5):             
...     print i
0
1
2
3
4
>>> li = ['a', 'b', 'c', 'd', 'e']
>>> for i in range(len(li)):       
...     print li[i]
a
b
c
d
e

 

>>> import os
>>> for k, v in os.environ.items():       
...     print "%s=%s" % (k, v)
USERPROFILE=C:\Documents and Settings\mpilgrim
OS=Windows_NT
COMPUTERNAME=MPILGRIM
USERNAME=mpilgrim

[...略...]
>>> print "\n".join(["%s=%s" % (k, v)
...     for k, v in os.environ.items()]) 
USERPROFILE=C:\Documents and Settings\mpilgrim
OS=Windows_NT
COMPUTERNAME=MPILGRIM
USERNAME=mpilgrim

[...略...]