Python/Tutorial

The following is a brief tutorial on the functionality of Python. This tutorial assumes no prior programming knowledge, but still assumes enough technical or mathematical competence to learn the language.

This tutorial assumes Python 3.14 or later. While the tutorial may reference features or concepts in other languages, these will be explained with context.

Hello World

The Hello World program in Python is as follows:

print("Hello, world!")

print() is a built-in function, which is used to display text, variables (we will explain what this is later) or output to the screen.

Variables

In Python, a variable is a named value which can store data in the computer's memory. You can think of this as a labelled storage box (with a name and contents), and can be re-used later.

A variable is created as soon as something is assigned to it, using the equals sign.

name = "Nate"
age = 19

Names can only contain letters, numbers and underscores; they must start with a letter or an underscore. Additionally, names are case-sensitive (so Age, age and AGE are three different names).

Finally, variables cannot have a keyword as a name.

In Python, the type of a variable may be changed at any time by re-assigning it:

x = 10
x = "Hello"

However, this is not good practice to reassign types, and we will avoid this in the tutorial.

Basic types

In Python, there are four basic types:

• int: a whole number, without any decimal points.
  • For example: 42, -7, 0
• float: a number with a decimal point.
  • For example: 3.14, 2.71, -0.005, 10.0
• str: a piece of text wrapped in a quote (single or double).
  • For example: "Hello", 'a', "nusoi", "67"
• bool: a logical value representing a truth state.
  • Only values: True, False

Type annotations

Python allows the user to explicitly indicate the type of a variable at declaration. For clarity, we will do this in this tutorial.

name: str = "Nate"
age: int = 19

Reading input

To read input in Python, use the built-in input() function. A text prompt may be passed inside this function, which will be printed. When a line with input() is hit, the program is paused, and waits for the user to enter something into the console.

username: str = input("Input your name: ")
print("Hello, " + username + "!")

Note that input() itself returns a str, and that all user text is always treated as a string.

If we wanted to use input as a number, we can use casting. Python offers the following conversions

• int(): converts a value to int
• float(): converts a value to float
• str(): converts a value to str
• bool(): converts a value to bool

This is an example of using the int() cast:

age: int = int(input("Enter your age: "))
print("Next year, you will be: ", age + 1)