What is the “right” way to iterate through an array in Ruby?

foreach (array/hash as $key => $value)

array.length.times do |i|
end

array.each

array.each_index

for i in array

hash.each do |key, value|

array = [1, 2, 3, 4, 5, 6]
array.each { |x| puts x }

1
2
3
4
5
6

array = ["A", "B", "C"]
array.each_with_index {|x, y| puts "#{x} => #{y}" }

A => 0
B => 1
C => 2

for index in 0 ... array.size
  puts "array[#{index}] = #{array[index].inspect}"
end

for key in hash.keys.sort
  puts "hash[#{key.inspect}] = #{hash[key].inspect}"
end

(1..10).each{|i| puts "i=#{i}" }

(1..10).to_a.reverse.each{|i| puts "i=#{i}" }

(a=*1..10).each{|i| puts "i=#{i}" }

(a=*1..10).reverse.each{|i| puts "i=#{i}" }

(*1..10).each{|i| puts "i=#{i}" }
(*1..10).reverse.each{|i| puts "i=#{i}" }
#
(1..10).step(1){|i| puts "i=#{i}" }
(1..10).step(-1){|i| puts "i=#{i}" }
#
(1..10).each{|i| puts "i=#{i}" }
(10..1).each{|i| puts "i=#{i}" }   # I don't want this though.  It's dangerous

class Range

  def each_reverse(&block)
    self.to_a.reverse.each(&block)
  end

end

ary.each_with_index { |val, idx| # ...

class Hash
    def each_pairwise
    	self.each { | x, y |
    		yield [x, y]
    	}
    end
end

class Array
    def each_pairwise
    	self.each_with_index { | x, y |
    		yield [y, x]
    	}
    end
end

["a","b","c"].each_pairwise { |x,y|
    puts "#{x} => #{y}"
}

{"a" => "Aardvark","b" => "Bogle","c" => "Catastrophe"}.each_pairwise { |x,y|
    puts "#{x} => #{y}"
}

['Home', '/', 'Page two', 'two', 'Test', 'test'].each_slice(2) do|label,link|
   li {a label, :href => link}
end

require 'enumerator'

['a',1,'b',2].to_a.flatten.each_slice(2) {|x,y| puts "#{x} => #{y}" }

# is equivalent to...

{'a'=>1,'b'=>2}.to_a.flatten.each_slice(2) {|x,y| puts "#{x} => #{y}" }

# Ruby 1.8
[1,2,[1,2,3]].flatten
=> [1,2,1,2,3]

# Ruby 1.9
[1,2,[1,2,3]].flatten(0)
=> [1,2,[1,2,3]]