TheDeveloperBlog.com
C-Sharp | Java | Python | Swift | GO | WPF | Ruby | Scala | F# | JavaScript | SQL | PHP | Angular | HTML
Ruby ROT13 Method
Develop a ROT13 method. ROT13 is a cipher that obscures the text content of strings.ROT13. ROT13 is a popular cipher. With it, we rotate characters in text forward, or backward, 13 places. This is an easily reversible cipher. In Ruby, we implement ROT13 with the tr method.
Example. First, we introduce the tr string method. This method receives two arguments: a string containing characters that are to be replaced, and a second string of the replacement characters.
Tip: The exclamation mark after tr means that tr will change the string in-place. We need to assign no variables.
Note: In the following examples, we refine our rot13 code, using a method and an abbreviated syntax for tr.
Ruby program that uses tr
# Input string.
value = "gandalf"
# Use tr to translate one alphabet to another.
value.tr!("abcdefghijklmnopqrstuvwxyz",
"nopqrstuvwxyzabcdefghijklm")
# Our result.
puts value
Output
tnaqnys
Def. Here we refine our approach and place the tr call inside a method. We use the def keyword to designate a method. In rot13(), we return the result of a tr call. When we call rot13 on the result of rot13, we get the original string back.Methods
Tip: In Ruby, a return keyword is not always needed. A single-statement method will automatically treat the statement as a return value.
Ruby program that uses def, rot13 method
def rot13(value)
return value.tr("abcdefghijklmnopqrstuvwxyz",
"nopqrstuvwxyzabcdefghijklm")
end
# Use rot13 method.
puts rot13("gandalf")
puts rot13(rot13("gandalf"))
Output
tnaqnys
gandalf
Ranges. The tr method can receive character ranges, like a regular expression. So the code "a-z" means the entire lowercase alphabet. We use this to rewrite the rot13 method. This version is shorter to type.Regexp
And: This method will have fewer possible typos. It is easier to review for correctness.
Ruby program that uses character ranges, tr
def rot13(value)
return value.tr("a-z", "n-za-m")
end
Summary. ROT13 is not encryption. It is easy to reverse. It is helpful to implement ROT13 in computer languages to learn how to manipulate strings. Often, languages contain helpful translate methods like tr.
© TheDeveloperBlog.com
The Dev Codes
Related Links:
- Ruby Convert Types: Arrays and Strings
- Ruby File Handling: File and IO Classes
- Ruby Regexp Match Method
- Ruby String Array Examples
- Ruby include: Array Contains Method
- Ruby Class Examples: Self, Super and Module
- Ruby DateTime Examples: require date
- Ruby 2D Array Examples
- Ruby Number Examples: Integer, Float, zero and eql
- Ruby Exception Examples: Begin and Rescue
- Top 65 Ruby Interview Questions (2021)
- Ruby on Rails Interview Questions (2021)
- Ruby String Examples (each char, each line)
- Ruby if Examples: elsif, else and unless
- Ruby Math Examples: floor, ceil, round and truncate
- Ruby Sub, gsub: Replace String
- Ruby Substring Examples
- Ruby Console: Puts, Print and stdin
- Ruby Remove Duplicates From Array
- Ruby Random Number Generator: rand, srand
- Ruby Recursion Example
- Ruby ROT13 Method
- Ruby Iterator: times, step Loops
- Ruby String Length, For Loop Over Chars
- Ruby Join Example (Convert Array to String)
- Ruby Format String Examples
- Ruby Copy Array Example
- Ruby Keywords
- Ruby Nil Value Examples: NoMethodError
- Learn Ruby Tutorial
- Ruby Method: Def, Arguments and Return Values
- Ruby Fibonacci Sequence Example
- Ruby Hash Examples
- Ruby While, Until and For Loop Examples
- Learn Ruby on Rails Tutorial
- Ruby Word Count: Split Method
- Ruby Sort Arrays (Use Block Syntax)
- Ruby Case Examples: Ranges, Strings and Regexp
- Ruby Array Examples
- Ruby Split String Examples