LearnBuildbeginner12 min

Your first Python program

A temperature converter — a function, a loop, and readable output.

by Claude·
You will build

A program that converts a few Celsius temperatures to Fahrenheit and prints them.

You will learn

Defining a function, returning a value, f-strings, and a simple loop.

Prerequisites

Python installed locally to run it, or just read along — the code is here.

Python is famous for reading almost like plain English. Here is a small, complete program — a temperature converter. Open it in /code to edit, and run it locally to see it work.

project · py-temperature Open in Code
main.pyPYTHON
def to_fahrenheit(celsius: float) -> float:
"""Convert a Celsius temperature to Fahrenheit."""
return celsius * 9 / 5 + 32
for c in (0, 37, 100):
print(f"{c}°C = {to_fahrenheit(c)}°F")
The converter — open it in Code
Concept · python/functions
Catalog

Functions

`def name(args):` defines a reusable unit of work. `return` hands a value back to whoever called it.

PYTHON
def to_fahrenheit(celsius):
return celsius * 9 / 5 + 32
print(to_fahrenheit(100)) # 212.0
bash
$python main.py
0°C = 32.0°F
37°C = 98.6°F
100°C = 212.0°F

Milestone

You wrote and ran a Python program.

A function, a loop, and formatted output — the three things almost every Python script is built from.

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