Regex Escape Characters

Backslash in /regex/ Expression

When you are trying to create a literal backslash match in Ruby, if you use the /regex/ expression, the backslash parsing are only done once. Meaning that \\ will become \ string literal.

For example: /\\h/ will be matching the TEXT "\h"

So in the context of /regex/ expression, you just need to escape it once

Backslash in Regexp.new Expression

However, if you are creating the regular expression via Regexp.new(expression), then the string you passed in will be parsed twice, that means \\ will become \, then become \ again then when used it basically means you didn't escape it at all.

The effect of \\ and \ is the same if used in Regexp.new(expression) because of the twice parsing.

If you want to actually match a string literal of "\" then you would have to input \\\\ which becomes \\ on first parse then \ on second parse for matching string literal \.