Check if a dictionary contains a key in Python

The Problem

How can I check whether a Python dictionary contains a given key?

The Solution

You can do this using Python’s in operator. When used with a dictionary, this will check its keys. For example:

prices = { "Apples": 1, "Oranges": 2 }

if "Oranges" in prices:
    print('prices dictionary contains key "Oranges"')

if "Pineapples" not in prices:
    print('prices dictionary does not contain key "Pineapples"')