workshop_1.md

Workshop 1 — Getting Started with Python

Prerequisites

• Python 3.12+ installed
• A text editor or IDE (VS Code, PyCharm, Sublime, or similar)

1. How does a computer work?

A computer runs on hardware (CPU, memory/RAM, storage) and software (the instructions that tell the hardware what to do). The CPU repeats a simple cycle millions of times per second:

1. Fetch — grab the next instruction from memory.
2. Decode — figure out what the instruction means.
3. Execute — carry it out.

Memory is organized into addressable bytes. Every value your program uses — a number, a piece of text — lives at some memory address while the program runs.

2. What is programming?

A computer only understands very simple instructions (add these two numbers, compare these two values, jump to this instruction). Writing useful software by hand in those terms would be unbearable, so we write source code in a programming language — a language designed to be readable by humans and translatable into instructions a computer can run.

3. What is Python?

Python is a high-level, interpreted, general-purpose programming language. "High-level" means it hides most hardware details from you. "Interpreted" means your code is run directly by the Python interpreter rather than compiled to machine code ahead of time.

4. Your first program

print("Hello, World!")

print(...) writes text to the console. Anything after a # on a line is a comment — the interpreter ignores it; it's there for humans.

# This line prints a greeting
print("Hello, World!")

5. The console

The console (or terminal) is a text-based way to run programs, as opposed to a GUI (graphical user interface) where you click buttons and icons. Run a Python file from the console with:

python3 workshop_1/calc.py

(On Windows, use py workshop_1/calc.py if plain python doesn't work or opens the Microsoft Store.)

6. Variables

A variable is a name that refers to a value stored in memory.

age = 25
name = "Ada"

Here, age refers to a memory location holding 25, and name refers to a different location holding "Ada". You can change what a variable refers to at any time by assigning it again.

7. Data types

Every value in Python has a type. The core types you'll use constantly:

Type	Meaning	Example
int	whole number	42
float	decimal number	3.14
str	text	"hello"
bool	true/false	True

Check a value's type with type(...):

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

8. Why data types matter

age = 25
print("Age: " + age)

This raises TypeError: can only concatenate str (not "int") to str. Python won't silently guess what you meant when combining a str and an int with +. This is deliberate — it catches real bugs early.

9. Type casting

Convert between types explicitly with int(...), float(...), and str(...):

age = 25
print("Age: " + str(age))   # works: both sides are now str

text_number = "10"
print(int(text_number) + 5)  # 15

10. f-strings

An f-string is a shortcut for building a string out of variables, without manually casting and concatenating with +. Put an f right before the opening quote, and any {variable} inside the string is replaced with its value:

name = "Ada"
age = 25
print(f"{name} is {age} years old")   # Ada is 25 years old

This works even when the variable isn't a str — f-strings convert it for you, so age doesn't need str(age) here.

11. Operators

Arithmetic:

Operator	Meaning	Example	Result
+	addition	2 + 3	5
-	subtraction	5 - 2	3
*	multiplication	4 * 3	12
/	division (always float)	7 / 2	3.5
//	floor division	7 // 2	3
%	modulo (remainder)	7 % 2	1
**	exponent	2 ** 3	8

Comparison (all return a bool):

Operator	Meaning	Example	Result
==	equal	3 == 3	True
!=	not equal	3 != 4	True
>	greater than	5 > 2	True
<	less than	5 < 2	False
>=	greater or equal	5 >= 5	True
<=	less or equal	5 <= 2	False

What's next

See workshop_1/ for runnable examples, and your homework in python-127-homework-1.