Python Basics

1. Getting set up

To write and run Python on your own computer:

1. Go to python.org and download the latest version of Python.
2. Run the installer. On Windows, tick “Add Python to PATH” before clicking Install.
3. Open IDLE (comes with Python) or install VS Code for a nicer editor.
4. Create a new file, save it as hello.py, and you’re ready to code.

2. Printing output

The print() function shows something on the screen.

print("Hello, world!")
print("My name is Alex.")

Hello, world!
My name is Alex.

3. Variables

Store information with an = sign. The name comes first.

name = "Priya"
age = 12
print(name, "is", age)

Priya is 12

4. Asking for input

Use input() to ask the user a question. Whatever they type is stored as text.

name = input("What is your name? ")
print("Hi,", name+"!")

age = int(input("How old are you? "))
print("Next year you will be", age + 1)

5. Doing maths

6. If / else

age = int(input("Your age? "))

if age >= 13:
    print("You are a teenager.")
elif age >= 5:
    print("You are at school.")
else:
    print("You are little!")

7. Loops

For loops repeat a fixed number of times:

for i in range(3):
    print("Hip hip hooray!")

While loops repeat as long as something is true:

lives = 3
while lives > 0:
    print("Still alive!")
    lives = lives - 1

8. Functions

A function is a reusable block of code. Define it once with def, then call it whenever.

def greet(name):
    print("Hello,", name+"!")

greet("Leo")
greet("Mia")

Hello, Leo!
Hello, Mia!