This question already has answers here: Check if a given key already exists in a dictionary (16 answers) Closed last month. Given: Which of the following is the best way to check if 'a' is in d? Answer in is definitely more pythonic. In fact has_key() was removed in Python 3.x.

Should I use ‘has_key()’ or ‘in’ on Python dicts? [duplicate]

Mateen Ulhaq

edited 10 Apr, 2022

igorgue

asked 24 Aug, 2009

Given:

>>> d = {'a': 1, 'b': 2}

JavaScript
​x
 
>>> d = {'a': 1, 'b': 2}
​

Which of the following is the best way to check if 'a' is in d?

>>> 'a' in d
True

JavaScript
 
>>> 'a' in d
True
​

>>> d.has_key('a')
True

JavaScript
 
>>> d.has_key('a')
True
​

in is definitely more pythonic.