/Python-wats

wat wat wat

Python-wats

Here's a small collection of wats I have come across while learning Python. This is also an attempt to learn Markdown.

True or False?

>>> True is False == False

Lets analyse from LHS, ie, (True is False) == False
True is False is False
False == False is True
So output should be True

Now, from the RHS, ie, True is (False == False)
False == False is True
True is True is True
So output should be True

But the output is..

False

wat?

Explanation:
a < b < c is interpreted as a < b and b < c
All expressions involving two or more operations are interpreted in a similar way.
So the given expression is equivalent to

>>> True is False and False == False

True is False is False and False == False is True
False and True is False Hence the result is

False

200 + 200 is 400?

>>> 10 + 10 is 20
True
>>> 20 + 30 is 50
True
>>> 100 + 100 is 200
True
>>> 200 + 200 is 400
False

waaat?

Explanation: Identity operator is not checking for equality, it is checking if the operands are pointing to the same memory bucket. For example,

>>> a = 2
>>> b = 2
>>> a is b
True

Here, a is b is True because id(a) is equal to id(b). That is, both a and b are pointing to the same memory bucket. This works for small integers. However,

>>> a = 260
>>> b = 260
>>> a is b
False

because, id(a) is not equal to id(b). For integer values greater than 255, a and b point to different memory buckets.

Now we can see why 10 + 10 is 20 is True and 200 + 200 is 400 is False. (200 + 200) does not point to the same location as 400.