ruby - Hashes and different syntax: getting nils as return values when trying to access key-values -

beginner programmer here who's been in couple of months.

assuming have block of code data structure:

users = { admin: "secret", admin2: "secret2", admin3: "secret3" } 

when try access value specific key so: users[:admin], return value of nil, if use syntax: users['admin'], return value of "secret". why happen? aren't these 2 syntaxes supposed equivalent according documentation.

side question: when create .yml file data structure, , try set this:

{ "admin" => "secret", "admin2" => "secret2", "admin3" => "secret3" } 

i not able load ("parse") file , error:

did not find expected ',' or '}' while parsing flow mapping @ line 1 column 1

but block of code in beginning fine. again, thought syntax supposed equivalent or perform same function. why happen? think weakest point in coding @ point hashes because confuses me much.

thanks in advance!

@borsunho correct in stating :admin , "admin" not equivalent. if have come rails background out understanding ruby can confusing since params hash not care. because params special class called hashwithindifferentaccess.

implementing not difficult besides question.

as yml file should be:

:admin: "secret" :admin2: "secret2" :admin3: "secret3" 

this parse out same original hash. syntax different yml way store data structures , independent of ruby or of syntax rules.

the leading colons mean symbol, otherwise keys parsed strings.

e.g.

require 'yaml' yml = <<yml   :admin: "secret"   :admin2: "secret2"   :admin3: "secret3" yml yaml.load(yml) #=> {:admin=>"secret", :admin2=>"secret2", :admin3=>"secret3"}  yml = <<yml   admin: "secret"   admin2: "secret2"   admin3: "secret3" yml  yaml.load(yml) #=> {"admin"=>"secret", "admin2"=>"secret2", "admin3"=>"secret3"}