Basic Data Types

Introduction

Python is a dynamically typed language, meaning you don't need to declare variable types explicitly. We'll start with Python's core data types: integers, floats, strings, booleans, and None.

Numbers

Python handles numbers intuitively:

# Integers
10 + 5    # 15
10 - 3    # 7
4 * 3     # 12
10 / 3    # 3.3333 (always returns float)
10 // 3   # 3 (floor division)
10 % 3    # 1 (modulus)
2 ** 8    # 256 (exponent)

Unlike some languages, Python's division operator / always returns a float. Use // for integer (floor) division.

Strings

Strings in Python can be created with single quotes, double quotes, or triple quotes for multi-line strings:

name = "SaneGenius"
greeting = 'Hello, World!'
multiline = """This is
a multi-line
string."""

# String formatting (f-strings - the modern way)
print(f"Welcome to {name}!")  # "Welcome to SaneGenius!"

# Common string methods
"hello".upper()       # "HELLO"
"HELLO".lower()       # "hello"
"hello world".title() # "Hello World"
"  hello  ".strip()   # "hello"
"hello".replace("l", "r")  # "herro"
len("hello")          # 5

Booleans and None

Booleans in Python are True and False (capitalized). None represents the absence of a value, similar to null in other languages.

is_active = True
is_deleted = False
result = None

# Falsy values in Python:
# False, 0, 0.0, "", [], {}, set(), None
bool(0)    # False
bool("")   # False
bool([])   # False
bool(42)   # True
bool("hi") # True

Type conversion

int("42")     # 42
float("3.14") # 3.14
str(42)       # "42"
bool(1)       # True
type(42)      # <class 'int'>

Assignment

Knowledge check

• What is the difference between / and // in Python?
• How do you format variables inside strings in Python?
• What values are considered "falsy" in Python?
• How do you convert between data types?