how to concatenate my strings with php in html

I know how to concatenate php variable but how about php if else script inside html? I have used below code:

    $output .='
    <div class="col-md-3 mb-4">
        <div class="card h-100">
          <img class="card-img-top"  src="../admin/upload/'. $row['images'].'" width="50px" height="300px" alt="Image">
          <div class="overlay">
            <p><strong> Title : </strong>'. $row['title'].'</p>
            <p><strong> Author : </strong>'. $row['author'].'</p>
            <p><strong> ISBN : </strong>'. $row['isbn'].'</p>

          </div>
          <div class="card-body">


            '.$status='';
            if ($row ['status'] == 'Available')
            {
              $status='success';
            }
            else if ($row ['status'] == 'Unavailable')
            {
              $status ='danger';
            }.'

<a href="book_details.php?title='. $row['title'].'&isbn='. $row['isbn'].'"> <button type="button"class="btn btn-'.$status.'">'. $row['status'].'</button></a>


          </div>
        </div>

      </div>';

How do I concatenate my strings especially when the php if else statement? Thanks for help

Answer

You can’t do that. The cleanest solution would be to put the if statement before the generation of $output i.e.

$status = $row ['status'] == 'Available' ? 'success' : 'danger';
$output .= '    <div class="col-md-3 mb-4">
    ...
          <div class="card-body">
<a href="book_details.php?title='. $row['title'].'&isbn='. $row['isbn'].'"> <button type="button"class="btn btn-'.$status.'">'. $row['status'].'</button></a>
    ...
    </div>';

For such large blocks of text, you might want to consider heredoc syntax. See this demo.