<?php
$string = ",a,b,c,,,d,,";
$string_new = '';
foreach($str as $data)
{
{
$string_new .= $data. ',';
}
}
PD9waHAKCiAgICAkc3RyaW5nID0gIixhLGIsYywsLGQsLCI7CiAgICAkc3RyID0gZXhwbG9kZSgiLCIsICRzdHJpbmcpOwogICAgJHN0cmluZ19uZXcgPSAnJzsKCWZvcmVhY2goJHN0ciBhcyAkZGF0YSkKCXsKCQlpZighZW1wdHkoJGRhdGEpKQoJCXsKCQkJJHN0cmluZ19uZXcgLj0gJGRhdGEuICcsJzsKCQl9Cgl9CgllY2hvIHN1YnN0cl9yZXBsYWNlKCRzdHJpbmdfbmV3LCAnJywgLTEpOw==