CODEWITHSUNDEEP
crystal-lang
Mraiih
Mraiih

Reputation: 171

use correctly String#tr method?

New to Crystal-lang, I'm actually trying to code a Caesar cipher. Problem is, when I enter a string to encode, the program show the same string without modification.

if ARGV.size < 3
  puts "./caesarcipher [ed] [text] [num]"
  exit
end

letter = ARGV[0]
str = ARGV[1]
n = ARGV[2].to_i
alphabet = ("A".."Z").to_a

case letter
when "e" then puts str.tr(alphabet.join, alphabet.rotate(n).join)
when "d" then puts str.tr(alphabet.join, alphabet.rotate(n * -1).join)
else          puts "./caesarcipher [ed] [text] [num]"
end

Since the two arguments in the tr method contain what I want and tr must return a value, I don't understand why nothing change.

Upvotes: 2

Views: 77

Answers (1)

SalmonKiller
SalmonKiller

Reputation: 2203

Welcome to Stack Overflow!

The reason why this didn't work for you, is because if you examine the alphabet array, it's actually only capital letters. So in your translation, you are only translating the upper case characters. If you instead change

alphabet=("a".."z").to_a

that will translate for the lower case characters.

If you want to do both, then I would suggest creating two "alphabets" one with upper and one with lower case letters, and then applying the translation twice on the string, one with upper and one with lower case alphabets.

Upvotes: 1

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