Let me clear up a common misconception. When most people say writing in code, what they really mean is writing using a cipher. A code is when a symbol, word, or phrase is used to stand for a different word, phrase, or sentence. A cipher is were each letter in a word is represented with a different letter or symbol.
The dash is a punctuation mark that is similar to a hyphen or minus sign, but differs from both of these symbols primarily in length and function.
An en dash (â) is most commonly used to indicate a range of numbers. It is longer than a hyphen although a hyphen with spaces surrounding it can be used if a dash is not available. In Microsoft Word, doing this will automatically change the hyphen into an en dash. (Example: August 13âAugust 18, or pages 29â349. Note that there should be no space around the en dash.)