Functions & basics
Reusable building blocks — parameters, returns, scope, and clear function design.
Calculate Time Difference Across Time Zones in Python
Compute the current time difference in hours between two time zones given their UTC offsets using Python's datetime and timezone modules.
from datetime import datetime, timezone, timedelta
def time_difference(from_tz_offset, to_tz_offset):
"""
Calculate time difference in hours between two time zones given their offsets from UTC.
Offsets are in hours (e.g., -5 for EST, +5.5 for IST).
"""
tz1 = timezone(timedelta(hours=from_tz_offset…How to Create Functions with Default Parameters in Python
This code defines two Python functions using default parameters to handle missing arguments gracefully, demonstrating how to work with optional inputs and keyword arguments.
def greet(name="Guest", greeting="Hello", punctuation="!"):
"""Generate a greeting message using default parameters."""
return f"{greeting}, {name}{punctuation}"
def create_profile(username="anonymous", age=0, city="Unknown", active=True):
"""Create a user profile dictionary with default values."""
r…How to Implement Memoized Fibonacci in Python with functools.cache
Use functools.cache to memoize a recursive Fibonacci function, avoiding repeated computation and dramatically speeding up the calculation.
from functools import cache
@cache
def fibonacci(n: int) -> int:
"""Return the n-th Fibonacci number (0-indexed)."""
if n < 2:
return n
return fibonacci(n - 1) + fibonacci(n - 2)
if __name__ == "__main__":
for i in range(10):
print(f"fibonacci({i}) = {fibonacci(i)}")
print(f"Cache…How to Invalidate Cache When Arguments Change in Python
A memoization decorator that caches function results keyed by arguments, automatically invalidating when inputs change.
from functools import wraps
def memoize(func):
cache = {}
@wraps(func)
def wrapper(*args, **kwargs):
key = (args, tuple(sorted(kwargs.items())))
if key not in cache:
cache[key] = func(*args, **kwargs)
return cache[key]
return wrapper
@memoize
def expensiv…Compound interest calculator in Python
Compute future investment value with the compound interest formula and a readable year-by-year loop.
def future_value(
principal: float,
annual_rate: float,
years: int,
compounds_per_year: int = 12,
) -> float:
"""Return balance after compound interest (rounded to cents)."""
rate_per_period = annual_rate / compounds_per_year
periods = compounds_per_year * years
amount = principal * (1 …Browse by section
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Functions & basics — Python code examples
What you will find here
This page collects functions & basics snippets — short, copy-ready Python you can paste into our free online IDE and run without installing anything. Each sample includes a plain-English explanation and the full source code.
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Samples are quick reference — one concept per page. For step-by-step teaching, use our Python tutorials. To test yourself, try quizzes or coding challenges. Clean up style with the Python formatter.