Notice: Only variables should be passed by reference in C:\xampp\htdocs\my\admin.php on line 35

Question

if(isset($_POST['btn_shoes']))
{
    if(isset($_FILES['img_shoes']))
    {
        $errors= array();
        $file_name = $_FILES['img_shoes']['name'];
        $file_size =$_FILES['img_shoes']['size'];
        $file_tmp =$_FILES['img_shoes']['tmp_name'];
        $file_type=$_FILES['img_shoes']['type'];
        $file_ext=strtolower(end(explode('.',$_FILES['img_shoes']['name']))); //line 35

Answer 1

This occurs because some PHP versions don't accept that you are passing a function directly to the another function.You must assign the function value to a variable and pass it to the strtolower function.See below:

$text = end(explode('.',$_FILES['img_shoes']['name']));
$file_ext=strtolower($text);