Python Standard Library
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The os and sys Modules
The os module lets you interact with the filesystem and operating system (listing directories, joining paths, reading environment variables), while sys exposes interpreter-level details like command-line arguments and the module search path -- together they're the bridge between your script and its environment.
Example: The os and sys Modules
import os
import sys
print(os.getcwd())
print(sys.platform)The datetime Module
The datetime module provides date, time, and datetime objects for representing points in time, plus timedelta for representing durations -- it handles the surprisingly tricky arithmetic of adding days across month boundaries or comparing two dates correctly.
Example: The datetime Module
from datetime import datetime, timedelta
now = datetime(2024, 1, 1)
print(now + timedelta(days=10))The random Module
random.random() and random.randint() generate pseudo-random numbers, and random.choice()/random.shuffle() work directly on sequences -- useful for anything from simulating dice rolls to shuffling a quiz question order, though it's not cryptographically secure.
Example: The random Module
import random
print(random.randint(1, 6))The json Module
json.dumps() converts a Python dict or list into a JSON-formatted string (encoding), and json.loads() does the reverse, parsing a JSON string back into native Python objects -- this is the standard way Python programs talk to web APIs that exchange JSON.
Example: The json Module
import json
data = {"name": "Alex"}
text = json.dumps(data)
print(text)
print(json.loads(text))The math Module
The math module supplies functions standard arithmetic operators don't cover, like math.sqrt(), trigonometric functions, math.log(), and rounding helpers like math.floor()/math.ceil() -- reach for it whenever you need more than +, -, *, and /.
Example: The math Module
import math
print(math.sqrt(16))
print(math.floor(4.7))
print(math.ceil(4.2))Chapter Quiz — Complete all 6 topics to unlock
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