Python

Variables

Declaration and typing

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# Boolean variables can only contain one of two values: True or False
#     Boolean values are annotated by using the "bool" keyword
a: bool = True
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# Integers are variables that contain any positive or negative whole number
#     Integers are annotated using the "int" keyword
# Floats are variables that contains any positive or negative decimal
#     Floats are annotated using the "float" keyword
a: int = 15
b: int = -23
 
c: float = 6.4
d: float = -9.5
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# Strings are variables that contain text
#     Strings are annotated using the "str" keyword
a: str = "This is a string"
b: str = 'Strings can be enclosed using single quotes'
 
# Initializing an empty string:
a = ""
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# Lists are collections of other variables
#     Lists are annotated using the "list" keyword
a: list = ["Some string", 15, 9.6, True]
 
# Initializing an empty list:
a = []
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# Sets are lists that cannot contain duplicate values
# They also do not keep the order of the variables
# Sets are a lot faster than lists when looking for specific values
#    Sets are annotated using the "set" keyword
a: set = {"Some string", 15, 9.6, True}
 
# Initializing an empty set:
a = set()
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# Tuples are lists that cannot be changed after being created
# They are useful when returning multiple values from a function
#     Tuples are annotated using the "tuple" keyword
a: tuple = ("Some string", 15, 9.6, True)
 
# Because tuples cannot be changed there is no point in initializing an empty one
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# Dictionaries work of Key - Value pairs
# Keys can be any immutable type - integers, floats, strings and tuples
# Dictionaries do not keep the their order
#     Dictionaries are annotated using the "dict" keyword
a: dict = {"A": "Some string", "B": 15, "C": 9.6, "D": True}
 
# Initializing an empty dictionary:
a = {}
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