Removing only letters

[dudejma]

I have read the PCRE page on PHP and I still don't understand. All I'm trying to do is simply remove the letters from this variable. I have a variable, for example "555tul,748den". I simply want to remove the letters, but keep the comma. Everywhere I've looked, all the examples remove the letters but remove the comma too. I need to keep the comma. Any suggestions? Much appreciated.

[Pikachu2000]

str_replace can do that . . .

 

$haystack = "555tul,748den";
$needles = array_merge( range('a', 'z'), range('A', 'Z') );
$new_str = str_replace( $needles, '', $haystack );

[dudejma]

Every time I try to use str_replace, I always mess something up. Thanks!