Format integer or string in php

sorry for a noob question but I am wondering if you could format strings in php with comma or dashes, something like this:

Ex. #1

Sample Input: 123456789
Formatted Output: 123,456,789 or 123-456-789

Ex. #2

Sample Input: 0123456789
Formatted Output: 012,3456,789 or 012-3456-789

If anyone could help me out, that would be appreciated.

Answer

You could use a regex replacement here:

function formatNum($input, $sep) {
    return preg_replace("/^(d{3})(d+)(d{3})$/", "$1".$sep."$2".$sep."$3", $input);
}

echo formatNum("123456789", ",");   // 123,456,789
echo "n";
echo formatNum("0123456789", "-");  // 012-3456-789