Php how to remove any last commas

Question

Example output

1. test,test,test,test,test,
2. test,test,test,,
3. test,test,,,
4. test,,,,,

I tried use implode according to my previous q

Answer 1

rtrim for example:

$str = 'foo,bar,blah,bleh,';
echo rtrim($str,',');

// foo,bar,blah,bleh