Should I use 'has_key()' or 'in' on Python dicts?

Question

I wonder what is better to do: d = {'a': 1, 'b': 2} 'a' in d Trueor: d = {'a': 1, 'b': 2} d.has_key('a') True

Answer 1

Use 'in' whenever possible with python collections. In the case of dictionaries the 'in' keyword uses the dictionaries hash-table instead of searching every key in stored order. Further, 'has_key()' no longer exists in python 3.x.