Printing

A program can have as many commands as you need. Lua carries them out one after another, from top to bottom, and each print prints a new line:

print("Good morning, Emma!")
print("The hens laid 7 eggs.")
print("Bella gave 12 liters of milk.")

This prints:

Good morning, Emma!
The hens laid 7 eggs.
Bella gave 12 liters of milk.

The lines in the output come in the same order as the commands in the program. When you swap two prints, their lines swap too.

A print() with nothing in the parentheses prints an empty line. It's handy for separating parts of the output:

print("Monday")
print()
print("Weather: sunny")

This prints:

Monday

Weather: sunny

A text can be written in double quotes, "Hello", or in single quotes, 'Hello'. Both mean the same, as long as the text starts and ends with the same kind of quote. In this course, we use double quotes. The other kind comes in handy when the text itself contains a quote or an apostrophe:

print("Emma's farm")
print('Rex says "Woof!"')

This prints:

Emma's farm
Rex says "Woof!"

In single quotes, print('Emma's farm') doesn't work: Lua thinks that the text ends at the apostrophe, then finds an s that makes no sense to it, and the program ends with an error. The same happens when the quotes at the start and at the end of a text differ, as in print("Hello'): Lua can't tell where the text ends.

Watch out for missing quotes, too. Without them, Lua doesn't read words as a text, but as names, such as the name of the function print:

• print(Good morning) ends with an error, because two names in a row make no sense to Lua.
• A single word without quotes doesn't even cause an error: print(Carrot) prints nil. Nothing in the program is called Carrot, and nil is Lua's word for “nothing”. You'll learn more about names and nil in the next lesson.