Vivienne Reay

Python syntax basics

Variables

A variable is like a labelled box where you store information. You create a variable by giving it a name and putting a value in it using the equals sign (=).

name = "Alice"
age = 25

Good variable names describe what's inside the box, so user_age is better than ua.

String quotes

Strings are text. You can write them with single quotes or double quotes—Python treats them the same.

greeting = 'Hello'
greeting = "Hello"  # Both work exactly the same

For longer text that spans multiple lines, use triple quotes:

message = """Hello,
this is a longer
message"""

You don't need to tell Python "this is text", it figures it out automatically when it sees quotes.

Data types

Python automatically knows what type of data you're storing. You don't have to tell it.

name = "Alice"    # Python knows this is text
age = 25          # Python knows this is a number

If you need to change a value from one type to another, you can do that later using functions like str(), int(), or float().

Case sensitivity

Python cares about uppercase and lowercase letters. These are three different variables:

name = "Alice"
Name = "Bob"
NAME = "Charlie"

Also, True and False must start with a capital letter. Writing true or false will cause an error.

Naming conventions

Write variable names in lowercase with underscores between words. This is called "snake_case":

my_variable = 10
user_age = 25
total_score = 100

Don't start names with numbers or use special characters (except underscores). These won't work:

25_age = 25        # Wrong! Can't start with a number
user-age = 25      # Wrong! Can't use hyphens

Whitespace and indentation

Python uses indentation (pushing code in from the left) to organise code. Incorrect indentation breaks your program, so be careful to keep it consistent.