Add x every Nth of $needle?

[aebstract]

I have a string that is unformatted and has a lot of commas in it. How would I add a \n linebreak after every 4th comma?

[Muddy_Funster]

Not sure this will work, but it's where I would start:

$str_array = explode(",", $unformatedString)
for ($i = 1; $i <= array_count($str_array); $i++){
if (isnumeric($i / 4) && $str_array[$i-1] != '\n'){
array_splice($str_array, $i-1, 0, '\n');
$i = 1
}
}
$unformatedReturn = implode(",", $str_array);