34 lines
1.1 KiB
Markdown
34 lines
1.1 KiB
Markdown
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# Exercise XX - caesar cipher
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Implement the legendary caesar cipher:
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> In cryptography, a Caesar cipher, also known as Caesar's cipher, the shift cipher, Caesar's code or Caesar shift, is one of the simplest and most widely known encryption techniques. It is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet. For example, with a left shift of 3, D would be replaced by A, E would become B, and so on. The method is named after Julius Caesar, who used it in his private correspondence.
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write a function that takes a string to be encoded and a shift factor and then returns the encoded string:
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```javascript
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caesar('A', 1) // simply shifts the letter by 1: returns 'B'
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```
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the cipher should retain capitalization:
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```javascript
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caesar('Hey', 5) // returns 'Mjd;
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```
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should _not_ shift punctuation:
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```javascript
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caesar('Hello, World!', 5) //returns 'Mjqqt, Btwqi!'
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```
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the shift should wrap around the alphabet:
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```javascript
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caesar('Z', 1) // returns 'A'
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```
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negative numbers should work as well:
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```javascript
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caesar('Mjqqt, Btwqi!', -5) // returns 'Hello, World!'
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```
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