how to search user input against a list in ruby? - ruby

Question

I need to create a simple program in ruby that will let me insert a bulk list of device IMEI numbers to check if they were already processed. Whenever I run the following code it always responds with "IMEI Not Found in database". It will reply with the last line of code always. Ive been researching for a couple days now and have decided to make a post now after being unsuccessful. Can someone please explain what I'm doing wrong?
imei_database = ["1", "2", "3"]
puts "Enter IMEIs"
imei = gets
if imei_database.include?(imei)
puts "IMEI Found in database"
else
puts "IMEI Not Found in database"
end

Answer 1

Problems
Your current code doesn't use String#chomp or other methods to remove the trailing carriage return from Kernel#gets. You are actually getting values like "1\n", so you won't find a match in your imei_database array.
You also haven't implemented any splitting, pattern matching, or parsing of your input values, so you currently can't process more than one item at a time. You'll need to iterate over some collection constructed from your input to do that.
Suggested Solutions
Here's some alternate code that shows one way to get the results you want, but in a more modular way. Note that the core of the heavy lifting is done with gets.chomp.split, which is a simple way to handle multi-valued input strings.
class IMEI_Status
def initialize
#imei_status = {}
imei_input
end
def report
found = 'IMEI Found in Database: %s'
not_found = 'IMEI Not Found in Database: %s'
#imei_status.map do |k, v|
p((v ? found : not_found) % k)
end
end
private
def db_lookup
# stubbed response
%w[1 2 3]
end
def imei_lookup(imei)
db_lookup.include? imei
end
def imei_input
print 'Enter space-separated IMEIs: '
gets.chomp.split.each do |imei|
#imei_status[imei] = imei_lookup(imei)
end
#imei_status
end
end
# Testing, using `1 4` as user input.
status = IMEI_Status.new
status.report
#=> ["IMEI Found in Database: 1", "IMEI Not Found in Database: 4"]
There are certainly other ways to deliver similar results, so you can adapt the approach to suit your needs.

Answer 2

Newline character escape required!
imei_database = ["1", "2", "3"]
puts "Enter IMEIs"
imei = gets
imei = imei.chomp
if imei_database.include?(imei)
puts "IMEI Found in database"
else
puts "IMEI Not Found in database"
end
imei = imei.gsub("\n","")
works too.

Answer 3

If item_database is large, many user entries are anticipated and execution speed is paramount you should use a proper database or first convert item_database to a set, assuming sufficient memory is available. Set lookups are very fast, nearly constant-time, comparable to key lookups in hashes (which is not suprising considering that sets are implemented with a hash under the covers).
require 'set'
imei_database = ["1", "2", "3"]
IMEI_DATABASE_SET = imei_database.to_set
#=> #<Set: {"1", "2", "3"}>
Then execute:
entry = gets.chomp
puts "IMEI #{entry}#{IMEI_DATABASE_SET.include?(entry) ? '' : ' Not'} Found in database"
Two examples:
entry = "2\n".chomp
#=> "2"
puts "IMEI #{entry}#{IMEI_DATABASE_SET.include?(entry) ? '' : ' Not'} Found in database"
IMEI 2 Found in database
entry = "4\n".chomp
#=> "4"
puts "IMEI #{entry}#{IMEI_DATABASE_SET.include?(entry) ? '' : ' Not'} Found in database"
IMEI 4 Not Found in database