Sorting array with multiple variables

Question

I am trying to create a program where by the user can enter multiple names. those names are then displayed under each other in alphabetical order, and print(display) every second name backwards. i have gone through several tutorials this is my second day using ruby.. here is what i have so far.

name_list = {}
puts 'please enter names seperated by a space:'
name_list = gets.chomp
names = name_list.split(" ")

to grab names...

names.sort do |a,b| a.upcase <=> b.upcase end
display = "#{names}"
for ss in 0...display.length
       print ss, ": ", display[ss], "\n"
end

to arrange them alphabetically and under each other. i am really struggling to mesh it all together i think i have got at least half a dozen errors in here...if i am on the wrong path could someone guide me to some info so i can start again??

EDIT

i also had this idea of using a class. but i would have to program the names in i wanted the user to be able to add info via the consol. class A

def initialize(name) @name = name end def to_s @name.reverse end end

>> a = [A.new("greg"),A.new("pete"),A.new("paul")]

>> puts a

What are you trying to achieve with the last loop? What is the expected output? — Wukerplank
– Wukerplank, Commented Oct 12, 2011 at 7:57

tokland · Accepted Answer · 2011-10-12 08:24:40Z

3

Problems in your code:

name_list defined as an empty hash at the top but not used.
split(" ") -> split
sort { |a, b| a.method <=> b.method } -> sort_by { |x| x.method } -> sort_by(&:method)
sort is not an in-place operation, assign the result (or directly use it).
display = "#{names}" -> display = names
for ss in 0...display.length -> enumerable.each_with_index { |item, index| ... }
don't write do/end in one-liners, use { ... }

I'd write:

puts 'Please enter names separated by spaces'
gets.split.sort_by(&:upcase).each_with_index do |name, index|
  puts "%s: %s" % [index, (index % 2).zero? ? name : name.reverse]
end

edited Oct 12, 2011 at 8:24

answered Oct 12, 2011 at 8:11

tokland

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1 Comment

legendary_rob Over a year ago

thanks man i thought i had a few problems!! yeah... i started using ruby just yesterday. the syntax is so simple is confusing. i am used to a lot of uniform procedures... you rock my socks..

Romain · Accepted Answer · 2011-10-12 08:32:36Z

2

A few pointers then:

names.sort do |a,b| a.upcase <=> b.upcase end # Will not modify the "names" array, but will return a sorted array.
names.sort! do |a,b| a.upcase <=> b.upcase end # Will modify the "names" array.

To display your names:

names.each_with_index do |name, index|
    if index % 2 == 0
        puts name
    else
        puts name.reverse
    end
end

edited Oct 12, 2011 at 8:32

answered Oct 12, 2011 at 8:00

Romain

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1 Comment

legendary_rob Over a year ago

so if i wanted to print them under eachother would i add /n at the end or the print name??

Gazler · Accepted Answer · 2011-10-12 08:04:11Z

1

puts 'please enter names seperated by a space`enter code here` :'
names = gets.chomp.split(" ")

names.sort! {|a,b| a.upcase <=> b.upcase }  # For a single line use {..} instead of do..end

names.each_with_index do |n,i|
  if i % 2 == 0
    p n
  else
    p n.reverse
  end
end

You can also use a ternary operator, I used the full if else block for readability in this case.

names.each_with_index do |n,i|
  p (i % 2 == 0) ? n : n.reverse
end

EDIT

command = ""
names = []
while command != "exit"
  puts 'please enter names seperated by a space`enter code here` :'

  command = gets.chomp!

  if command == "display"
    names.sort! {|a,b| a.upcase <=> b.upcase }  # For a single line use {..} instead of do..end        
    names.each_with_index do |n,i|
      if i % 2 == 0
        p n
      else
        p n.reverse
      end
    end
  else
    names << command
  end
end

edited Oct 12, 2011 at 8:04

answered Oct 12, 2011 at 7:50

Gazler

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4 Comments

Romain Over a year ago

I'd generally avoid the ternary operator because it impairs readability of the code. In this case however, it's an OK-ish situation to use it. Also, OP sorts in a case-insensitive manner, you should do the same.

legendary_rob Over a year ago

thanks man.. would it be possible to put in a trigger say he could enter as many names as he wants but when he types "display" for instance then it will display the names.. by the way you rock my socks. i have used my google-fu and couldnt get anywhere :)

Gazler Over a year ago

@Romain, well spotted. I have changed that.

Gazler Over a year ago

@Sliknox I have updated my code to do this quickly before I head to work. It should do the trick though.

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