Adding results from datedif in foreach loop

Question

Is it possible to add the results in a datediff in a foreach loop? I am showing a page for time clock punches and want to add each shift in the end to display the total hours for the pay period. I had tried a few things from searching around and nothing came anywhere to fruition. I am not even sure that I am on the right path on how to complete this. If I am way off please point me in the right direction so I may learn the right process to take.

 @foreach($punches as $row)

                        <tr>
                            <?php $start= date_create($row->time_in);
                                   $end= date_create($row->time_out)
                            ?>

                            <td>{{date_format($start, "m-d-Y H:i")}}</td>

                            @if($row->time_out === NULL)
                            <td>
                                {!! Form::open(['url' => route('timeclock.update', $row->id), 'method' => 'POST']) !!}
                                @method('PUT')
                                @csrf

                                {{ Form::hidden('time_out', date('Y-m-d H:i:s')) }}


                                <button type="submit" class="btn btn-outline-warning btn-rounded waves-effect">Clock Out</button>

                                {!! Form::close() !!}
                                </td>
                            @else  
                            <td>{{date_format($end, "m-d-Y H:i")}}</td>
                            @endif

                            @if($row->time_out === NULL)
                            <td>Calculation Pending</td>
                            @else  
                            <?php
                            $interval = $start->diff($end);


                            ?>
                            <td>{{$interval->format('%h Hours %i minutes')}}</td>
                            @endif

                        </tr>
                        @endforeach