How to add value to an array inside of a hash with ruby

Question

contacts_r = File.open("user_contacts.txt", "r")

user_contacts = []
contacts_r.readlines.each { |line|
  user_contacts << line.chomp
}

$c = Hash[user_contacts.map { |x| ["$#{x}_called", Array.new] } ]

When I try to add info in the desired array...

$c["#{name}_called"] << 1

I get a undefined method '<<' for nil:NilClass (NoMethodError)

when I use..

puts $c

the output looks like

{"$robert_called"=>[]}

I'm trying to make it look like

{"$robert_called"=>[1]}

What is name? If it's not "robert", the error is obvious. Your code otherwise looks okay. (I'd probably contract the whole thing into user_contacts = File.read(filename).lines.map(&:chomp) or the lazier user_contacts = File.open(filename) { |f| f.each_line.map(&:chomp) }, and use a hash with a default proc (c = Hash.new { |h, k| h[k] = [] }) so I don't have to initialise it at all... Also, beware global variables, they have a nasty habit of biting you in the behind. — Amadan
– Amadan, Commented Nov 10, 2015 at 6:17
by "#{name}" i just meant thats where the namesgo...its no actualy part of the code :\ @Amadan — marriedjane875
– marriedjane875, Commented Nov 10, 2015 at 8:02

rohit89 · Accepted Answer · 2015-11-10 11:03:31Z

1

You forgot to prepend $.

$c["$#{name}_called"] << 1

edited Nov 10, 2015 at 11:03

answered Nov 10, 2015 at 6:24

rohit89

5,7833 gold badges28 silver badges42 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Cary Swoveland Over a year ago

...and $[k] => nil (i.e., the value of key k is nil) if the hash does not have a key k, so $c[k] << 1 becomes nil << 1. nil is the one and only instance of NilClass. NilClass has no instance method :<<, which means that nil has no method :<<. That's precisely what the error message is telling you. Study error messages carefully. Often they pinpoint the problem.

marriedjane875 Over a year ago

your right, I forgot to put the $ in the array name. And i'm still considerably new (not even a year) so I'll pay more attention to what the errors are saying, thanks. :)

Collectives™ on Stack Overflow

How to add value to an array inside of a hash with ruby

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related