php - Regular expression to only allow whole numbers and commas in a string

Question

Does anyone know what the preg_replace would be for a string to only allow whole numbers and commas? I want to strip all whitespace, letters, symbols, etc, so all that is left is numbers and commas, but without any leading or training commas in the string. (Example: 5,7,12)

Here is what I am using now and it only strips whitespace before and after the commas but allows anything else, I think.

$str = trim(preg_replace('|\s*(?:' . preg_quote($delimiter) . ')\s*|', $delimiter, $str));

Answer 1

This should do what you need:

$str = preg_replace(
  array(
    '/[^d,]/',    // Matches anything that's not a comma or number.
    '/(?<=,),+/',  // Matches consecutive commas.
    '/^,+/',       // Matches leading commas.
    '/,+$/'        // Matches trailing commas.
  ),
  '',              // Remove all matched substrings.
  $str
);