daterange.php

function format_date_range($start_date, $end_date, $start_time = null, $end_time = null){
  
  $start_date = new \DateTime($start_date);
  $end_date = new \DateTime($end_date);
  $return = '';

    if($start_date->format('d/m/Y') != $end_date-> format('d/m/Y')){
        $return .= 'Du '.$start_date->format('d/m/Y').' ';
        if($start_time){
            $return .= $start_time.' ';
        }
        $return .= 'au '.$end_date->format('d/m/Y').' ';
        if($end_time){
            $return .= $end_time.' ';
        }
    }
    else{
        $return .= 'Le '.$start_date->format('d/m/Y').' ';
        if($end_time){
            $return .= 'de '.$start_time.' à '.$end_time;
        }
        else{
            if($start_time){
                $return .= 'à '.$start_time;
            }
        }
    }
    return $return;
}