PHP how to remove and add commas

Question

How to remove extra commas and add commas, for example using PHP

User Submitted Data

stack,,,,,,,,,,,,,,overflow

should be displayed.

stack, overflow

Answer 1

$out = preg_replace("/,+/",", ",$in);

Answer 2

preg_replace('/[,]+/', ',', $string); should do it ... although depending on the nature of the input, you may need a more complex expression.

Answer 3

$str = preg_replace('/,+/' , ',' , $str);

This will replace each sequence of one or more commas with one comma.