<?php

preg_match_all('<(?P<key>\w+)\:(?P<value>\d+)>', 'foo:23,bar:42', $matches);
var_dump($matches);

array(5) {
  [0]=>
  array(2) {
    [0]=>
    string(6) "foo:23"
    [1]=>
    string(6) "bar:42"
  }
  ["key"]=>
  array(2) {
    [0]=>
    string(3) "foo"
    [1]=>
    string(3) "bar"
  }
  [1]=>
  array(2) {
    [0]=>
    string(3) "foo"
    [1]=>
    string(3) "bar"
  }
  ["value"]=>
  array(2) {
    [0]=>
    string(2) "23"
    [1]=>
    string(2) "42"
  }
  [2]=>
  array(2) {
    [0]=>
    string(2) "23"
    [1]=>
    string(2) "42"
  }
}