Python Fundamentals: Syntax, Data Types & Gotchas

3 1 3.5

-4 1

1.0 3 2

tud fox xofyduts

[0, 4, 16]

[2, 5, 8]

[1, 2, 3, 4]

[[1, 2, 99], [3, 4]]

[1] [1, 2]

True False

False True False True

False , None , 0 , 0.0 , 0j , "" , and empty containers like [] , () , {} , set() and range(0) . Everything else is truthy.

False

3 [1, 2]

TypeError: 'str' object does not support item assignment

Mutable: list , dict , set , bytearray . Immutable: int , float , bool , str , tuple , frozenset , bytes .

list : ordered, mutable, allows duplicates. tuple : ordered, immutable. set : unordered, unique items, fast membership tests. dict : key-value pairs with unique keys (insertion-ordered since Python 3.7).

0 None True False

(1, 2) {'x': 3}

0 a 1 1 b 2

['fig', 'pear', 'apple']

10

UnboundLocalError : count is treated as local inside inc() because it is assigned there, but it is read before being assigned.

Python's name lookup order: Local, Enclosing function, Global (module), Built-in

try except finally

5 0

3.14 1,234,567

Rex canine

The with statement is a context manager: it closes the file automatically when the block ends, even if an exception is raised.

None