Implode sorted number array to string by commas and merge intervals

Question

I would like to implode an array, but with one difference. I would like to merge intervals with a - sign. How can this be done? (The array is ordered!)

Answer 1

There is no function like this, therefore you will need to create one yourself. I just created a sample function how this may look like, there are many possible solution for this (Did not try if it actually works, as I do not have a webserver in reach atm)

 paste 'prevValue,value''
     $o .= $lastValue . "," . $v;
    } else {
     //Check if there is a , sign at the end
     if((stripos(strrev($o), ',') === 0)) {
      // No - but , => paste 'value'
      $o .= $v;
     } else {
      // No - and no , => paste ',value'
      $o .= ",".$v;
     }         
    }
   }
  } else {
   $o = $v;
  }

  $lastValue = $v;
 }
 //Check if the implode has the last number set correctly
 if((stripos(strrev($o), '-') === 0)) {
  $o .= $lastValue;
 }
 return $o;
}

echo implodeNumberArray(array(1,2,3,6,8,9));
?>