[PHP-DEV] Deprecate b-prefix for strings

All,

The b string prefix and the (binary) cast were both introduced in PHP 5.2.1 for forward compatibility with PHP 6.

In 2016, there was an RFC [1] targeting PHP 7.x to deprecate both, which was declined.

Since then, the (binary) type cast has now been deprecated in PHP 8.5.0 [2], but as far as I can see, the b-prefix for strings is still supported.

I can’t remember ever coming across this in the wild, so I wonder if it might be a good idea to deprecate the b-prefix now as well.

I’ll happily create an RFC for this if the you all think it’s a good idea.

Opinions ?

Smile,
Juliette

1: https://wiki.php.net/rfc/binary_string_deprecation
2: https://wiki.php.net/rfc/deprecations_php_8_5#deprecate_non-standard_cast_names

Hi

On 2026-09-25 13:32, Juliette Reinders Folmer wrote:

I'll happily create an RFC for this if the you all think it's a good idea.

I do. You can probably just add an entry to PHP 8.7's bulk RFC: PHP: rfc:deprecations_php_8_7

Best regards
Tim Düsterhus