ROT-13 in Every Language
Published on 20 November 2018 (Updated: 02 May 2020)
ROT-13 is a letter substitution cipher where every letter is replaced by the
letter 13 letters after it alphabetically and wrapping from Z to A if necessary:
ABCDEFGHIJKLMNOPQRSTUVWXYZ -> NOPQRSTUVWXYZABCDEFGHIJKLM
As a result, encrypted strings can be decrypted using the same algorithm:
NOPQRSTUVWXYZABCDEFGHIJKLM -> ABCDEFGHIJKLMNOPQRSTUVWXYZ
Requirements
Write a sample program that takes a string of text as input. It should then encrypt the inputted text using ROT-13 and output the result to the console.
$ ./rot-13.lang "the quick brown fox jumped over the lazy dog"
gur dhvpx oebja sbk whzcrq bire gur ynml qbt
The solution should handle both lower case and capital letters
$ ./rot-13.lang "THE QUICK BROWN FOX JUMPED OVER THE LAZY DOG"
GUR DHVPX OEBJA SBK WHZCRQ BIRE GUR YNML QBT
Any characters/symbols besides a-z and A-Z should be ignored.
$ ./rot-13.lang "The quick brown fox jumped. Was it over the lazy dog?"
Gur dhvpx oebja sbk whzcrq. Jnf vg bire gur ynml qbt?
In addition, there should be some error handling for situations where the user doesn’t supply any input.
Testing
The following table contains various test cases that you can use to verify the correctness of your solution:
| Description | Input | Output |
|---|---|---|
| No Input | “Usage: please provide a string to encrypt” | |
| Empty Input | ”” | “Usage: please provide a string to encrypt” |
| Sample Input: Lower Case | the quick brown fox jumped over the lazy dog | gur dhvpx oebja sbk whzcrq bire gur ynml qbt |
| Sample Input: Upper Case | THE QUICK BROWN FOX JUMPED OVER THE LAZY DOG | GUR DHVPX OEBJA SBK WHZCRQ BIRE GUR YNML QBT |
| Sample Input: Punctuation | The quick brown fox jumped. Was it over the lazy dog? | Gur dhvpx oebja sbk whzcrq. Jnf vg bire gur ynml qbt? |
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