Ruby loop create empty lines

Question

I'm newbie in Ruby (frankly, I've just started learning it for fun, without any future plans), and I've noticed strange behaviour of loops. I assume my problem comes from lacks in knowledge in the mechanics of Ruby.

boysNames = ["Martin", "Lucas", "John"]

#class only for one method. I know it's not absolutely correct, but huh I'm just learning Ruby
class Human
    def initialize(name)
        @name = name;
    end
   String name = ""

   def getName()
       puts @name;
    end
end

Array boys = []




#create objects
for x in boysNames
    tempBoy = Human.new(x)
    boys.push(tempBoy)
end

#output for class

puts "Method 1: for in loop \n"
for x in boys
    puts x.getName()
end


puts "\nMethod 2: manual array[var] \n"
boys[0].getName()
boys[1].getName()
boys[2].getName()

puts "\nMethod 3: .each do \n"
boys.each do |i|
    puts i.getName()
end

#output for Array

puts "Method 1: for in loop \n"

for x in boysNames
    puts x
end


puts "\nMethod 2: manual array[var] \n"
puts boysNames[0]
puts boysNames[1]
puts boysNames[2]

puts "\nMethod 3: .each do \n"
boysNames.each do |i|
    puts i
end


#loop through the boys array
puts "\nboys array:  \n"
for x in boys
    puts x
end

So my question is: Why when I loop through the array everything is fine, and when I loop through the class, my results are divided by newlines? Are there any "invisible" objects that I couldn't find? As you can see my last loop found only three objects with different places in the memory.

I will be pleased, if the answer contains explanation of "how it works".

Thank you in advance ;)

P.S. Output:

Method 1: for in loop 
Martin

Lucas

John


Method 2: manual array[var] 
Martin
Lucas
John

Method 3: .each do 
Martin

Lucas

John

Method 1: for in loop 
Martin
Lucas
John

Method 2: manual array[var] 
Martin
Lucas
John

Method 3: .each do 
Martin
Lucas
John

boys array:  
#<Human:0x007f2a586db788>
#<Human:0x007f2a586db648>
#<Human:0x007f2a586db5d0>

P.S.S. I'm using this as the Ruby interpreter/compiler (I heard that Ruby can also be compiled, so...)

Since you're learning, I'll point out some coding style you should be aware of. You don't need type annotations such as `String name`, just go for `name`. Same with `Array boys = []`, just use `boys = []`. And Ruby uses `snake_case` rather than `camelCase`. I always like checking community driven best practices repos such as [this](https://github.com/bbatsov/ruby-style-guide) to learn the language more idiomatically! Hope it helps. Have fun learning Ruby, it's a wonderful language! — Frank Kair, Sep 16 '17 at 15:17
Thank you for helpful advices. `String name` lets me know what's type of data is 'name'. When it comes to code optimization I absolutely agree with you I wasn't aware of snake_case habit in Ruby. Good to know! — Tomasz Durda, Sep 16 '17 at 15:26

score 4 · Accepted Answer · answered Sep 16 '17 at 15:12

4

You're calling puts x.getName(), but getName() already has puts inside of it.

puts adds a newline to the end of each argument if there is not one already.

print does not add a new line.

(What is the difference between print and puts?)

answered Sep 16 '17 at 15:12

Frank Kair

451
4
13

Thank you. It's such a stupid mistake, that I flush when I think about it :D – Tomasz Durda Sep 16 '17 at 15:22
3

Actually, since "puts" always returns nil, the method `getName` returns nil. `puts nil` results in an empty string (from nil.to_s) plus a newline (added by `puts`). – steenslag Sep 16 '17 at 15:56

Ruby loop create empty lines

1 Answers1