Variables, Data Types, Numbers & Casting

Variables store values. You assign with = — no type keyword needed.

Python Variables

Variables store values. You assign with = — no type keyword needed.

Use snake_case names like user_name. Start with a letter, not a number.

Real-life example: A variable is a labeled box in storage — the label stays, but you can swap what is inside.

Creating variables

course = "Python Zero to Pro"
lesson = 3
print(course, lesson)

Common types: str (text), int (whole numbers), float (decimals), bool (True/False), list, tuple, set, dict.

Use type() to inspect a value's type at runtime.

Real-life example: Data types are like container shapes — you would not pour soup into a letter envelope (str vs list).

Core types

name = "Meera"       # str
age = 21             # int
gpa = 3.8            # float
active = True        # bool
print(type(name), type(age))

int handles whole numbers; float handles decimals. Python supports +, -, *, /, //, %, and **.

Division / always returns float. // is floor division.

Real-life example: int is counting whole apples; float is weighing flour on a kitchen scale.

Number operations

a, b = 10, 3
print(a + b, a / b, a // b, a % b, a ** b)

Casting converts one type to another: int(), float(), str(), bool().

Wrap risky conversions in try/except when reading user input.

Real-life example: Casting is like converting rupees to dollars — same value, different format for the receiver.

Type conversion

text = "42"
number = int(text)
print(number + 8)

value = str(99)
print("Score: " + value)