When to use int() and when to use var: int

Question

I am wondering when you use the var: int and when to you use the int(var).

For example:

def func(var: int, var2):

    print(var - int(var2))

Answer 1

The var: int used to know the type of the variable that is expected to be and pass it to a desired function or class, while int(var) will cast var variable to be an instance of int class:

>> a = '3' # a is String

>> a = int(a)

>> a

out: 3 # a is Integer now

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