Reading and Writing UTF-8 from Query String PHP

Question

I need to be able to pass music sharp and flat symbols around in a query string and also display in a utf-8 browser. The displaying part is straight-forward by using html entity representations for sharp and flat symbols.

Flat -  ♭
Sharp - ♯

It's the passing around of this data that has me stumped.

Let's take the chord symbol B flat: B♭
It's representation with HTML entities is: B♭

Client
To pass it I url-encode it: B%26%239837%3B
Then I feed that in my query string: ?lookup=B%26%239837%3B

Server
Read it: $r = urldecode($_GET['lookup']);
Display it: echo $r; Just get B

So then I tried:

Read it: $r = $_GET['lookup'];
Display it: echo $r; Just get B

Also the raw request just shows B.

How do I pass this type of url-encoded html entity around correctly in the query string?

Answer 1

This would be more straight-forward if you used actual UTF-8 encoded characters instead of HTML entities.

B%26%239837%3B is the URL encoded version of B♭. B♭ is the HTML entity representation of "B♭", it is not "UTF-8". What you want is B%E2%99%AD, which is the URL-encoded UTF-8 representation of "B♭". If you'd do $_GET['lookup'] on that, you'd get the UTF-8 encoded string "B♭".

You should keep everything in UTF-8 front to back. Please see Handling Unicode Front To Back In A Web App and possibly What Every Programmer Absolutely, Positively Needs To Know About Encodings And Character Sets To Work With Text for details.