Ruby From Beginning
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Hello World
#!/usr/bin/ruby puts "Hello World!"
What is your name?
#!/usr/bin/ruby
print "What is your name? "
name = gets
puts "Your name is #{name}"
Heredocument
#!/usr/bin/ruby print <<EOF This is the first way of creating here document ie. multiple line string. EOF
ARGS from the Console
#!/usr/bin/ruby puts ARGV[0] puts ARGV[1] puts ARGV[2]
Read a file
#!/usr/bin/ruby
puts "What file do you want to read? "
Filename = gets
Filename.delete!("\n")
TheFile = File.read( Filename )
puts TheFile.to_s
Write in a file
#!/usr/bin/ruby
puts "write"
VarFile = File.new("dat.txt", "w+")
VarFile.puts "das erste "
VarFile.puts "das zweite"
VarFile.close
IF Statement
#!/usr/bin/ruby
puts "Number?: "
x = gets
if x.to_i > 2
puts "x is greater than 2"
elsif x.to_i <= 2 and x.to_i != 0
puts "x is 1"
else
puts "I can't guess the number"
end
CASE Statement
#!/usr/bin/ruby print "Enter your grade: " grade = gets.chomp case grade when "A" puts 'You pretty smart!' when "B" puts 'You smart!' when "C", "D" puts 'You pretty dumb!!' else puts "You can't even use a computer!" end
WHILE Statement
#!/usr/bin/ruby
$i = 0
$num = 5
while $i < $num do
puts("Inside the loop i = #$i" )
$i +=1
end
FOR Statement
#!/usr/bin/ruby
for i in 0..5
puts "Value of local variable is #{i}"
end
OR
#!/usr/bin/ruby
(0..5).each do |i|
puts "Value of local variable is #{i}"
end
Methods
#!/usr/bin/ruby
def test(a1 = "Ruby", a2 = "Perl")
puts "The programming language is #{a1}"
puts "The programming language is #{a2}"
end
Class
#!/usr/bin/ruby
class Sample
def hello
puts "Hello Ruby!"
end
end
Instance of a class
object = Sample.new object.hello
Everything is a class
1.upto(3) { |i| puts i } # 1 2 3
3.downto(1) { |i| puts i } # 3 2 1
0.step(10,2) { |i| puts i } # 0 2 4 6 8 10
3.times { puts "42" } # 42 42 42