如何测试字典中的键是否存在? [英] How to test if a key in a dictionary exists?
问题描述
有没有人知道如何测试,例如,字典''name''是否有一个名为''name_key的
键''?
这是可能的:
keys_of_names = names.keys()
L = len (keys_of_names)
for i in range(L):
if keys_of_names [i] == name_key:
print' '找到''
但肯定没有效率。我希望有类似的东西:
name.is_key(name_key)
感谢您的帮助!
>
Frank
Hi,
does anyone know how one can test if, e.g., a dictionary ''name'' has a
key called ''name_key''?
This would be possible:
keys_of_names = names.keys()
L = len(keys_of_names)
for i in range(L):
if keys_of_names[i] == name_key:
print ''found''
But certainly not efficient. I would expect there is something like:
name.is_key(name_key)
I appreciate your help!
Frank
推荐答案
Frank写道:
Frank wrote:
有没有人知道如何测试一个字典''name''是否有一个名为''name_key'的
键?
Hi,
does anyone know how one can test if, e.g., a dictionary ''name'' has a
key called ''name_key''?
name_key名称
例如
name_key in name
e.g.
>> name = {" john":42}
" john"名称
>>name={"john": 42}
"john" in name
True
True
>>" julie"名字
>>"julie" in name
False
- Irmen
False
--Irmen
是的,你有name.has_key(name_key),或许更好,在
运算符中:
如果name_key在名称中:
做点什么
Yes, you have name.has_key(name_key) and perhaps better, the in
operator:
if name_key in name:
do something
当然,你可以使用if key in dict测试会员资格:
Python 2.3.5(#1,2006年1月13日,20:13:11)
[GCC 4.0.1(Apple Computer,Inc。)在达尔文建立5250)]
键入帮助,版权,信用等。或许可证或欲获得更多信息。
Sure, you can use "if key in dict" to test for membership:
Python 2.3.5 (#1, Jan 13 2006, 20:13:11)
[GCC 4.0.1 (Apple Computer, Inc. build 5250)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>> exampledict = {" a" :1,b :2}
a在exampledict
>>exampledict = {"a" : 1, "b" : 2}
"a" in exampledict
True
True
>>" q"在exampledict
>>"q" in exampledict
False
False
>>>
>>>
或者,exampledict.has_key(" a)"也是有效的。
请参阅:
http://docs.python.org/tut/node7.htm...00000000000000
-Jeff >
2007年3月10日13:17:11 -0800,Frank< su ****** @ gmail.comwrote:
Alternatively, "exampledict.has_key("a")" is also valid.
See:
http://docs.python.org/tut/node7.htm...00000000000000
-Jeff
On 10 Mar 2007 13:17:11 -0800, Frank <su******@gmail.comwrote:
有没有人知道如何测试,例如,字典''name''有一个名为''name_key'的
键'?
这是可能的:
keys_of_names = names.keys()
L = len( keys_of_names)
for i in range(L):
if keys_of_names [i] == name_key:
print''发现''
但肯定没有效率。我希望有类似的东西:
name.is_key(name_key)
感谢您的帮助!
>
Frank
-
http://mail.python.org/mailman/listinfo/python-list
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