regex - PHP code to remove everything but numbers

Question

I'm trying to remove everything from a string but just numbers (0-9).

I thought this would work..

echo preg_replace("[^0-9]","",'604-619-5135');

But it echos "604-619-5135". What am I missing???

Answer 1

Try this:

preg_replace('/[^0-9]/', '', '604-619-5135');

preg_replace uses PCREs which generally start and end with a /.