不要写空数组字段

ik have a html form where i can select some options. I want to write those values comma separated to my database. This is the code i have

$genretotal = $_POST['genre'];
$genre0 = $genretotal[0];
$genre1 = $genretotal[1];
$genre2 = $genretotal[2];
$genre3 = $genretotal[3];
$genre4 = $genretotal[4];
$genre5 = $genretotal[5];
$genre6 = $genretotal[6];
$genre7 = $genretotal[7];
$genre = $genre0 . "," . $genre1 . "," . $genre2 . "," . $genre3 . "," . $genre4 . "," . $genre5 . "," . $genre6 . "," . $genre7;

How can i leave out the empty values?

Try with implode and array_filter

implode(',', array_filter($_POST['genre']));

Why so?

$genre = join(',', array_filter($_POST['genre'], function($sItem)
{
   //here I assume your 'not empty' matches PHP empty() function
   //if not, then add desired conditions
   return !empty($sItem);
}));

$genretotal   =  $_POST['genre'];
if(isset($genretotal) && count($genretotal)>0)
{//This check array is null or not
    $gen_arr = implode(",",$genretotal);


}//end if
 echo $gen_arr;

//This is the code you avoid empty values