How to remove %EF%BB%BF in a PHP string

Question

I am trying to use the Microsoft Bing API.

$data = file_get_contents("http://api.microsofttranslator.com/V2/Ajax.svc/Speak?appId=APPID&text={$text}&language=ja&format=audio/wav");
$data = stripslashes(trim($data));

The data returned has a ' ' character in the first character of the returned string. It is not a space, because I trimed it before returning the data.

The ' ' character turned out to be %EF%BB%BF.

I wonder why this happened, maybe a bug from Microsoft?

How can I remove this %EF%BB%BF in PHP?

Answer 1

You should not simply discard the BOM unless you're 100% sure that the stream will: (a) always be UTF-8, and (b) always have a UTF-8 BOM.

The reasons:

1. In UTF-8, a BOM is optional - so if the service quits sending it at some future point you'll be throwing away the first three characters of your response instead.
2. The whole purpose of the BOM is to identify unambiguously the type of UTF stream being interpreted UTF-8? -16? or -32?, and also to indicate the 'endian-ness' (byte order) of the encoded information. If you just throw it away you're assuming that you're always getting UTF-8; this may not be a very good assumption.
3. Not all BOMs are 3-bytes long, only the UTF-8 one is three bytes. UTF-16 is two bytes, and UTF-32 is four bytes. So if the service switches to a wider UTF encoding in the future, your code will break.

I think a more appropriate way to handle this would be something like:

/* Detect the encoding, then convert from detected encoding to ASCII */
$enc = mb_detect_encoding($data);
$data = mb_convert_encoding($data, "ASCII", $enc);