Numbers, Booleans & None

Python values have types. The five you will use constantly:

| Type | Meaning | Example | | --- | --- | --- | | int | whole numbers | 42, -7 | | float | decimal numbers | 3.14, -0.5 | | str | text | "hello", 'a' | | bool | truth values | True, False | | NoneType | "no value" | None |

Type inspection

type(x) returns a value's type — indispensable while learning:

type(42)        # <class 'int'>
type(42.0)      # <class 'float'>
type("42")      # <class 'str'>

Note 42 vs 42.0 vs "42" — three different types. Python cares.

Conversion

Convert explicitly with int(), float(), str():

int("42")       # 42
float("3.5")    # 3.5
str(99)         # "99"
int("3.5")      # ValueError! int() refuses decimal text

Conversions between numbers and text are how programs talk to humans: input arrives as text; math needs numbers; output goes back to text.

Why None exists

None means "nothing here yet" — the placeholder for a result you do not have. You will meet it constantly once functions arrive.