sprintf function not evaluating

I'm trying to remove non-RFC characters after filtering a URL with other methods. This method breaks:

$query = 'www.example.com_-.su_-.1Mk8ij_-.www.cs.cmu.edu_-.~mjw_-.recipes_-.cheese_-.cheese-garlic-biscuits.html';

$query = preg_replace('/([^a-zA-Z0-9._-])/e', 'sprintf("_-%2.2x", ord($1))', $query);

The error returned is

Failed evaluating code: \开发者_运维知识库nsprintf("_-%2.2x", ord(~))

It breaks on other examples as well and I can't figure out why. Can anyone point me in the right direction?

Because the $1 is getting filled in already due to variable interpolation, and thus you're trying to call ord(~) instead of ord("~"). Use "$1" instead of $1.

$query = preg_replace('/([^a-zA-Z0-9._-])/e', 'sprintf("_-%2.2x", ord("$1"))', $query);

The clue is ord(~). A literal passed to ord should be quoted.

It should be 'sprintf("_-%2.2x", ord("$1"))', notice the double quotes around $1.