Difference between is and == in Python








  • Difference between is and ==

    In python, is is used to check for identity and == is used to check for equality.
    is will return True if two variables point to the same object.
    == will return True if the objects referred to by the variables are equal.


  • difference between == and is

    >>> list1 = [1, 2, 3]
    >>> list2 = list1
    >>> list2 is list1
    True
    >>> hex(id(list1))
    0x2faaf857e00
    >>> hex(id(list2))
    0x2faaf857e00
    list2 is list1 returned True because both list1 and list2 refer to the same object as they have the same memory address (on this machine, it is 0x2faaf857e00)




  • difference between is and ==

    >>> list1 = [1, 2, 3]
    >>> list2 = list1[:]
    >>> list2 is list1
    False
    >>> hex(id(list1))
    0x2faaf896300
    >>> hex(id(list2))
    0x2faaf900dc0
    list2 is list1 returned False because list1 and list2 are different object and they have different memory addresses (on this machine, list1 is stored at 0x2faaf896300 and list2 at 0x2faaf900dc0)



  • What is the difference between difference between is and ==

    >>> list1 = [1, 2, 3]
    >>> list2 = list1
    >>> list2 == list1
    True
    >>> list1
    [1, 2, 3]
    >>> list2
    [1, 2, 3]
    List2 == list1 returned True because both list1 and list 2 have the same value (in this example, [1, 2, 3])



  • is Vs ==

    >>> list1 = [1, 2, 3]
    >>> list2 = list1[:]
    >>> list2 == list1
    True
    >>> list1
    [1, 2, 3]
    >>> list2
    [1, 2, 3]
    List2 == list1 returned True because both list1 and list 2 have the same value (in this example, [1, 2, 3])




  • == Vs is

    The operator is and its counterpart is not are used for checking object identity, they check if objects refer to the same instance (same address in memory).
    The operator == and its counterpart != are used for checking equality (same value), they check if objects have same value or not.
  • difference between is and == in Python

    As a rule of thumb, a is b implies a == b (except for odd things like floating point NaNs that compare inequal to themselves).
    • a == b does not imply a is b.
    • Operator is cannot be overloaded.
    • Operator == can be overloaded.


  • difference between is and == in Python

    Small integers (-5 to 256) behaves differently because CPython implementation optimizes the storage of integers in the range (-5 to 256) by making them singletons. Each (small) integer value is mapped to a single value, so every 3 is identical and equal. This is an implementation detail, not part of the language specification.





  • difference between == and is in Python

    Comparisons to singletons like None should always be done with is or is not, never the equality operators

  • difference between is and == in Python

    == is typically used to see equality of
    • integers
    • floats
    • strings
    • lists
    • sets
    • dictionaries

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