>>> 'a' in vars()
False
>>> a = 1
>>> 'a' in vars()
True
>>> b = 2
>>> locals()
Python中其实有蛮多方法可以判断一个变量是否已经定义了。方法一:tryexcept[mw_shl_code=python,true]def
isset(v):
try
:
type
(eval(v))
except
:
return
0
else
:
return
1
[/mw_shl_code]用法:[mw_shl_code=python,true]if
isset('user_name'):
'user_name
is
defined'
else
'user_name
is
not
defined'
[/mw_shl_code]方法二:使用命名空间[mw_shl_code=python,true]'varname'
in
locals().keys()'varname'
in
dir()[/mw_shl_code]推荐使用第二种方法来判断