格式化字符串（3.5）

1.字符串格式化时不一定用tuple，也可以直接用"%uid"这样的形式 

>>> uid='qj'
>>> uid
'qj'
>>> password = 'jin'
>>> password
'jin'
>>> uid + password
'qjjin'
>>> print "%s password %s"%(uid,password)
qj password jin
>>> i = 10
>>> print "%s password %d"%(uid,i)
qj password 10
>>> print "%s password"(uid,)

Traceback (most recent call last):
  File "<pyshell#35>", line 1, in <module>
    print "%s password"(uid,)
TypeError: 'str' object is not callable
>>> print "%s password"%(uid,)
qj password
>>> print "%s password"%(uid)#this pattern also print the right answer
qj password
>>> print "%s password"%uid#so does this one
qj password
>>>

2.使用"for exp in values"时，exp的格式要与values里面一个元素的格式对应，否则会出现下面的错误

 >>> params = {"server":"mpilgrim", "database":"master", "uid":"sa", "pwd":"secret"}
>>> params
{'pwd': 'secret', 'database': 'master', 'uid': 'sa', 'server': 'mpilgrim'}
>>> [k for k in params.keys()]
['pwd', 'database', 'uid', 'server']
>>> [k for k,v in params.keys()]

Traceback (most recent call last):
  File "<pyshell#42>", line 1, in <module>
    [k for k,v in params.keys()]
ValueError: too many values to unpack
>>>  

 

3.字符串list的jion

>>> "-".join([k for k,v in params.items()])
'pwd-database-uid-server'
>>>