5 Getting Started
- Get started with the python console
- Learn the basic python syntax
5.1 Overview
This page and the next few pages will roughly follow along with the live coding session. We will use the expense calculator script as a basis. The next sections in the course materials are for reference and contain cheat sheets and notes, for you to look back at when you need. In the session, most of the information will be taught to you within the live coding and using the exercises, however in some cases the course materials will have more information which could be useful in certain situations. In particular, there are reference tables for operators, data types and templates for functions.
5.2 Getting Started The Terminal and python console
5.2.1 What is the terminal?
The terminal is a text-based interface that lets you type commands directly to your computer’s operating system. Instead of clicking buttons or menus, you write commands for opening files, running programs, or installing software.
5.2.2 The terminal in VS Code
In Visual Studio Code (VS Code), the terminal is built-in. You can open it from the menu (View → Terminal) or by pressing a shortcut (often Ctrl+`). It appears at the bottom of the editor and works just like your computer’s command line, but directly inside VS Code.
5.2.3 Using the terminal to run a script
To run a python script from the terminal use:
python script_name.py
Note 1 You need to be in the correct directory to run a python script from the terminal. It should automatically open into the current directory in VSCode - e.g. where the expense_calculator.py is located
note that you likely do not want to use your system python to run scripts as this is used by the operating system
You should have installed python in the setup. sometimes it can be python3
5.2.4 Using the terminal to open the python Console
A console is a text-based interface that allows a user to interact directly with a computer system or software by entering commands and receiving text-based output.
The Python console, also known as the Python interpreter or REPL (Read–Evaluate–Print Loop), is an interactive environment that allows users to write and execute Python code one statement at a time. It is particularly useful for testing small code snippets, exploring language features, debugging, and learning Python syntax. When a line of code is entered, the interpreter immediately evaluates it and displays the result, enabling rapid feedback and experimentation. In the Python console, users can execute expressions, define variables and functions, and import modules. However, code written in the console is not saved automatically; for reusable or larger programs, Python scripts (.py files) are preferred.
To open python interactively in the terminal, in the terminal window type: python It will offer a prompt:
Python 3.9.6 (default, Oct 4 2024, 08:01:31)
[Clang 16.0.0 (clang-1600.0.26.4)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> Attend our course on unix command line
If you’re interested in using the terminal more, for example to navigate file systems and automate tasks - attend the training facilities unix course
5.3 Assigning variables
A variable is a named reference used to store and access a value in a program.
In Python initialising variables is easy:
Variables are assigned using the = sign
Case sensitive
No need to declare the type explicitly (dynamic typing)
# Initialising my_height in cm
my_height = 176
my_name = "Kavi"
### Variable Naming Conventions in Python - Making your life easy!
One of the worst things in particular when looking at other peoples code is variable names that make no sense to anybody but the writer
When naming variables, it’s important to follow Python’s guidelines for consistency and readability. Here are some key rules to remember:
Case-sensitive: weight and Weight are different variables.
Use lowercase: Separate words with underscores, e.g., weight_kg.
Don’t start with numbers: Variable names cannot begin with a digit.
Stick to letters: Use only letters, underscores, and digits (when needed).
Be descriptive: Choose clear, meaningful names (e.g., asdjks is not helpful).
Avoid overly long names: For example ‘this_is_my_height_in_cm’ is too long.
Don’t use keywords: Avoid using Python function names, class names, or data types as variable names.
For more detailed guidelines, refer to PEP 8 or the Google Python Style Guide.
5.3.1 Indentation
In python indentation is used to define code blocks. We will see more of this later when we get to conditional statements and loops. - Unexpected indents will result in errors. - indents are 4 spaces according to PEP 8 standards, however commonly also two spaces on web interfaces. Be consistent. - Using spaces is preferable to using tabs
# Initialising my_height in cm
my_height = 176
my_name = "Kavi"
The above would produce an error
5.4 Commenting your code
Commenting your code, and using lines liberally, are key to making your code easily understandable for both yourself and others. These comments are ignored by python and do not result in any output - check for yourself in the console!
A
#(Hash) is used for single line commentsA
"""(triple quotes) is used around multiline comments or stringsA
\(backslash) is used to explicitly break a lineLines can be implicitly continued in some cases, for example when in brackets. We will see this later.
5.5 Summary
- Variables are words used to reference and access a value
- Be clear an concise following guidelines when naming variables
- Comment your code for clarity