/[A-z]/

/[A-z]/

/[A-Z\[\\\]^_`a-z]/
```

Now it's much clearer why the expression wasn't working the way I intended it to!

## What To Use Instead

If the **whole regex** can be case-insensitive, the easiest thing to do is use the case insensitive modifier, `i`:

```rb
/[a-z]/i
```

If only a **certain part** of your expression can be case-insensitive, there are a couple of options. For example, let's say we are looking for a three-character, letter-only string where the first and last character are lowercase but the middle character can be uppercase or lowercase. How would we write that?

One option would be to do this:

```rb
/[a-z][a-zA-Z][a-z]/
```

Another way to do this would be to [specify modes inline](https://www.regular-expressions.info/modifiers.html) with the expression. This allows you to turn on the case insensitive mode for a portion of your rexpression. Here's what that could look like:

```rb
/[a-z](?i)[a-z](?-i)[a-z]/
```

> Note: Specifying these modes inline may not work for all programming languages.

## Wrapping Up

I'm actually glad I came across this issue. It was a great learning experience and it was helpful to see how the ranges in regex work. I thought it would be good to share this here in case anyone else comes across this in the future. Hopefully this is helpful to someone! 

*Thanks for reading!*