PHP从我的循环中删除最后一个字符

Question

I'm writing a string from my form and I'd like to remove the last comma from the end. I understand that I can use the rtrim(), but I don't understand how I can return a variable from my loop. I'm sure this is an easy answer, just super confused. Thanks!

if (isset($_POST['submit'])) {

foreach ( $_POST['data'] as $data )
{

    echo $data['Monday'];
    echo $data['Tuesday'];
    echo $data['Wednesday'];
    echo $data['Thursday'];
    echo $data['Friday'];
    echo $data['Saturday'];
    echo $data['Sunday'];
    echo ", ";
}

} // end if

Answer 1

You can check if you are on the last element and skip printing the comma if so:

end($_POST['data');             // fast forward to the end of the array
$lastKey = key($_POST['data');  // and remember what the last key is

foreach ( $_POST['data'] as $key => $data )
{
    echo $data['Monday'];
    echo $data['Tuesday'];
    echo $data['Wednesday'];
    echo $data['Thursday'];
    echo $data['Friday'];
    echo $data['Saturday'];
    echo $data['Sunday'];
    if ($key !== $lastKey) echo ", ";
}

This approach feels cleaner to me: prevention is better than treatment.