Your first program: print()

Telling Python to print something

To make Python show something on the screen, you use print. It's a functionfunctionA named piece of code that does a job when you call it. You call it by writing its name followed by parentheses.: a small tool with a name that does one job. You put what you want to show inside the parentheses.

Press Run below.

print("Selam, Mawj!")

The text between the quotes is a stringstringText inside your code, written between quotes. Python shows it exactly as you typed it.. Python doesn't try to understand it. It shows it exactly as you wrote it, without the quotes. Click into the code, change the words, and run it again. You just edited a program.

A program can have many lines. Python runs them from top to bottom, one at a time, and each print starts on a new line.

print("Good morning, Hana.")
print("Your macchiato is ready.")
print("That will be 45 birr.")

Words and numbers

Numbers don't need quotes. Without quotes, Python treats a number as a number, which means it can do arithmetic with it before printing.

print(250)
print(250 + 30)
print(1200 - 350)

With quotes, the same characters become text, and Python shows them as they are. Before you run anything, decide what this prints.

print("2 + 3")
print(2 + 3)

2 + 3
5

Printing more than one thing

You can give print several values at once, separated by commas. Python puts a single space between them. This is how you mix text and numbers on one line.

print("Total:", 120, "birr")

Total: 120 birr

That space is only the default. Two extra settings change how print joins things and how it finishes:

• sep is what goes between values. It's a space unless you say otherwise.
• end is what goes after the last value. It's a new line unless you say otherwise.

print("27", "09", "2026", sep="/")
print("Loading", end="...")
print("done")

The first line joins three values with / instead of spaces. The second line ends with ... instead of a new line, so the next print continues on the same line. Try changing sep="/" to sep="-" and run it again.

When Python doesn't understand you

Sooner or later, and usually sooner, Python will stop and show you an errorerrorPython's message when it can't run your code. The last line names the problem.. This is normal. Programmers see errors all day. The trick is to read the last line first: it names the problem.

Here's the most common one in a first program.

A SyntaxError means Python couldn't even read the line. A different kind of error happens when the line reads fine but uses a name Python doesn't know. Run this, read the last line of the error, and fix it.

prnt("Selam")

Python says NameError: name 'prnt' is not defined, and even suggests print. Add the missing letter and run it again.

The same program on your computer

Everything so far ran in your browser. Once Python is installed, you can run the exact same code from a file. You'll do this properly in the next lesson; here's the short version.

1. Make a file

   In VS Code, create a file called hello.py and type print("Selam, Mawj!") into it. Save it.

2. Open a terminal in that folder

   In VS Code, open Terminal, then New Terminal. It opens in your project folder.

3. Run it

   Type the command for your system and press Enter.

   WindowsmacOSLinux

   Windows

   py hello.py

Python prints Selam, Mawj! on the next line of the terminal, just as it did here.