Variables and Data Types in Python

Python is a dynamically typed language, meaning you don’t need to explicitly declare variable types. The interpreter infers the type based on the assigned value.

Creating Variables

In Python, variables are created the moment you assign a value:

# String variable
name = "Alice"

# Integer variable
age = 30

# Float variable
height = 5.9

# Boolean variable
is_student = True

Data Types

Python has several built-in data types:

Numeric Types

Type	Description	Example
int	Integer numbers	42
float	Floating point	3.14
complex	Complex numbers	3+4j

Text Type

message = "Hello, World!"
multiline = """This is a
multiline string."""

Sequence Types

• List: Ordered, mutable collection → [1, 2, 3]
• Tuple: Ordered, immutable collection → (1, 2, 3)
• Range: Sequence of numbers → range(0, 10)

Type Checking

Use type() to check a variable’s type:

x = 42
print(type(x))  # <class 'int'>

y = 3.14
print(type(y))  # <class 'float'>

Type Casting

Convert between types using built-in functions:

# String to Integer
num = int("42")

# Integer to Float
decimal = float(42)

# Number to String
text = str(3.14)

Best Practices

1. Use descriptive variable names (user_count not uc)
2. Follow snake_case naming convention
3. Use constants in UPPER_CASE (MAX_RETRIES = 3)
4. Avoid single-letter variables except in loops

Tip: Python 3.10+ supports structural pattern matching, which can simplify type-based logic.