Here is an example:
max = 10
if ARGV.size > 0
max = ARGV[0].to_i
end
puts "I'm choosing a number between 1 and #{max}"
num = rand(max) + 1
loop do
print "Enter guess: "
reply = STDIN.gets.chomp.to_i
if reply == num
puts "You guessed it"
break
elsif num < reply
puts "Lower"
else
puts "Higher"
end
end