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There is a magic array named `ARGV`.
It contains the *command line arguments* to the program.
If the user types:
ruby hello.rb Alice Bob
then ARGV contains:
# Why ARGV?
ARGV is a historical name. It means "Argument Vector" and has been around since the early 1970s.
# Command-Line Hello
Change `hello.rb` to contain:
puts "Hello, " + ARGV
and run it a few times, e.g.
ruby hello.rb Alice
# LAB: Hello, Everyone!
Change `hello.rb` to say hello to *every one* of its command line arguments.
ruby hello.rb Alice Bob Charlie
# LAB: Add
Write a program named `add.rb` that adds all of its command line arguments together.
ruby add.rb 1 2 3
Do you remember how to convert a string to an integer?