301_loops.txt

#  basics


while true
  puts "'looped' one iteration by design"
  var1 = gets

  break           # break out of the otherwise infinite loop
end


while true
  puts "This will loop forever!"
  var1 = gets
  
  next    # got to the next iteration of the infinite loop
  break
end



for i in 0..5
   puts "Value of local variable is #{i}"
end










a = [1, 2, 3]  # make an array


a.each do |element|
  puts element          # loop through each element within the array
end


a.each { |element|
  puts element          # Same thing but with brackets
}


a.each { |element| puts element}       # same thing but on one line



a.map { |element| element.to_s + " hi"}        # woah, big difference!  This one returns an array of length == a.length
=> ["1 hi", "2 hi", "3 hi"]

a.map { |element| element.to_s + " yo"}        # woah!  and the contents of each array slot are the return of the block... 
=> ["1 yo", "2 yo", "3 yo"]                    # (e.g. element.to_s + " hi")


a.map(&:to_s)        # shortened up drastically, but less flexable


# notice
User.first.following.map(&:id)
=> [4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42,
43, 44, 45, 46, 47, 48, 49, 50, 51]





a.map do |element|
  puts element
end






a = ["1", "", "2", "3", "", nil]


a.compact                           # loops through and kicks out all the nil members
=>  ["1", "", "2", "3", ""]       


a.reject(&:empty?)                  # loops through the array and kicks out all the empty members    
=> ["1", "2", "3"]







a = [1, 2, 3]
out = []

a.each.with_index do |element, i|         # loops through, but gives you the index variable 
  out[i] = element                        # so you don't manually have to create and incriment it
end