# Rotational Cipher in R

#### Create an implementation of the rotational cipher, also sometimes called the Caesar cipher.

1 | ```
exercism fetch r rotational-cipher
``` |

# Rotational Cipher

Create an implementation of the rotational cipher, also sometimes called the Caesar cipher.

The Caesar cipher is a simple shift cipher that relies on
transposing all the letters in the alphabet using an integer key
between `0`

and `26`

. Using a key of `0`

or `26`

will always yield
the same output due to modular arithmetic. The letter is shifted
for as many values as the value of the key.

The general notation for rotational ciphers is `ROT + <key>`

.
The most commonly used rotational cipher is `ROT13`

.

A `ROT13`

on the Latin alphabet would be as follows:

It is stronger than the Atbash cipher because it has 27 possible keys, and 25 usable keys.

Ciphertext is written out in the same formatting as the input including spaces and punctuation.

## Examples

- ROT5
`omg`

gives`trl`

- ROT0
`c`

gives`c`

- ROT26
`Cool`

gives`Cool`

- ROT13
`The quick brown fox jumps over the lazy dog.`

gives`Gur dhvpx oebja sbk whzcf bire gur ynml qbt.`

- ROT13
`Gur dhvpx oebja sbk whzcf bire gur ynml qbt.`

gives`The quick brown fox jumps over the lazy dog.`

## Installation

See this guide for instructions on how to setup your local R environment.

## How to implement your solution

In each problem folder, there is a file named `<exercise_name>.R`

containing a function that returns a `NULL`

value. Place your implementation inside the body of the function.

## How to run tests

Inside of RStudio, simply execute the `test_<exercise_name>.R`

script. This can be conveniently done with testthat's `auto_test`

function. Because exercism code and tests are in the same folder, use this same path for both `code_path`

and `test_path`

parameters. On the command-line, you can also run `Rscript test_<exercise_name>.R`

.

## Source

Wikipedia https://en.wikipedia.org/wiki/Caesar_cipher

## Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.