Python: Checking if a 'Dictionary' is empty doesn't seem to work

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Chapters
00:00 Question
00:34 Accepted answer (Score 1090)
01:05 Answer 2 (Score 201)
01:27 Answer 3 (Score 29)
01:41 Answer 4 (Score 21)
02:04 Thank you

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Full question
https://stackoverflow.com/questions/2317...

Accepted answer links:
[evaluate to ]: https://docs.python.org/2/library/stdtyp...

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Content licensed under CC BY-SA
https://meta.stackexchange.com/help/lice...

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Tags
#python #dictionary

#avk47

ACCEPTED ANSWER

Score 1221

Empty dictionaries evaluate to False in Python:

>>> dct = {}
>>> bool(dct)
False
>>> not dct
True
>>>

Thus, your isEmpty function is unnecessary. All you need to do is:

def onMessage(self, socket, message):
    if not self.users:
        socket.send("Nobody is online, please use REGISTER command" \
                    " in order to register into the server")
    else:
        socket.send("ONLINE " + ' ' .join(self.users.keys()))

ANSWER 2

Score 238

Here are three ways you can check if dict is empty. I prefer using the first way only though. The other two ways are way too wordy.

test_dict = {}

if not test_dict:
    print "Dict is Empty"


if not bool(test_dict):
    print "Dict is Empty"


if len(test_dict) == 0:
    print "Dict is Empty"

ANSWER 3

Score 35

d = {}
print(len(d.keys()))

If the length is zero, it means that the dict is empty.

ANSWER 4

Score 33

Simple ways to check an empty dict are below:

a = {}

```
if a == {}:
  print ('empty dict')
```
```
if not a:
  print ('empty dict')
```

Method 1 is more strict, because when a = None, method 1 will provide the correct result, but method 2 will give an incorrect result.