The first thing you need to learn in any programming language is the famous
Hello World! program.
In Crystal this is pretty simple, maybe a little bit boring:
puts "Hello World!"
You can build and run code examples interactively in this tutorial by clicking the
Run button (thanks to carc.in).
The output is shown directly inline.
puts is short for “put string”.
The entire program consists of a call to the method
puts with the string
Hello World! as an argument.
This method prints the string (plus a trailing newline character) to the standard output.
All code in the top-level scope is part of the main program. There is no explicit
main function as entry point to the program.