Inconsistent printing with Ruby

Question

I am trying to print a ruby hash:

opts = {
  'one' => '1',
  'two' => '1',
  'three' => '0'
}

I want the output to be

one=1
two=1
three=0

This works fine with this code on one machine which runs ruby 1.8.7

print opts.map{|k,v| k + '=' + v + "\n"}.to_s

But on a different machine which runs ruby 1.9, it prints

["one=1\n", "two=1\n", "three=0\n"]

What is going wrong?

score 5 · Accepted Answer · edited May 23 '17 at 12:11

5

Try

print opts.map{|k,v| k + '=' + v + "\n"}.join

The explanation is easy: With ruby 1.9 Array.to_s changed its behaviour.

An alternative:

puts opts.map{|k,v| k + '=' + v }.join("\n")

or

puts opts.map{|k,v| "#{k}=#{v}" }.join("\n")

I would prefer:

opts.each{|k,v| puts "#{k}=#{v}" }

And another version, but with another look:

opts.each{|k,v| puts "%-10s= %s" % [k,v]}

The result is:

one       = 1
two       = 1
three     = 0

(But the keys should be not longer then the length in %-10s.)

edited May 23 '17 at 12:11

Community

answered Jul 31 '13 at 20:37

knut

score 4 · Answer 2 · answered Jul 31 '13 at 20:37

4

It's working as expected. Give this a try:

a={:one=>1, :two=>2, :three=>3}
a.each {|k,v| puts "#{k}=>#{v}" }

answered Jul 31 '13 at 20:37

jblack

You forgot the `newline` :) – Nir Alfasi Jul 31 '13 at 20:37
@alfasin nope, hi did not ;) – David Unric Jul 31 '13 at 20:43
You got +1 from me then :))) – Nir Alfasi Jul 31 '13 at 20:44
@alfasin The `puts` add its own newline. But there is an additional `>` ;) – knut Jul 31 '13 at 20:44

score 1 · Answer 3 · answered Jul 31 '13 at 20:36

1

Try:

res = ""
opts.map{|k,v| res += k + '=' + v + "\n"}
puts res

answered Jul 31 '13 at 20:36

Nir Alfasi

It's really redundant to create a local variable for just printing Hash's content. – David Unric Jul 31 '13 at 20:42
@DavidUnric right, there's a waste of two bytes on the stack... ;) – Nir Alfasi Jul 31 '13 at 20:46
@alfasin Too optimistic etsimate for a full String class instance. – David Unric Jul 31 '13 at 21:19
@DavidUnric touche! :) – Nir Alfasi Jul 31 '13 at 21:25
@alfasin ```Memory.analyze("one=1\ntwo=2\nthree=3\n")``` # – David Unric Jul 31 '13 at 21:28
@DavidUnric well, that's still not much, is it ? :))) – Nir Alfasi Jul 31 '13 at 21:38

3 Answers3