How can I check if a key exists in a dictionary? [duplicate]

Answer 1

if key in array:
  # do something

Associative arrays are called dictionaries in Python and you can learn more about them in the stdtypes documentation.

Answer 2

Another method is has_key() (if still using Python 2.X):

>>> a={"1":"one","2":"two"}
>>> a.has_key("1")
True

Answer 3

If you want to retrieve the key's value if it exists, you can also use

try:
    value = a[key]
except KeyError:
    # Key is not present
    pass

If you want to retrieve a default value when the key does not exist, use value = a.get(key, default_value). If you want to set the default value at the same time in case the key does not exist, use value = a.setdefault(key, default_value).