相关疑难解决方法(0)

运行我的脚本时,我收到几个这样的错误:

警告:不能更改头信息-头已经发出(输出开始/some/file.php:12)在/some/file.php上线23

错误消息中提到的行包含header()和setcookie()调用.

这可能是什么原因？以及如何解决它？

我的代码 -

if ($result) 
{
    $row = $result->fetch_object();
    $filename = $row->src;

    $q = "delete from photos WHERE id=$fileid";
    $result = $mysqli->query($q) or die(mysqli_error($mysqli));
    if ($result) 
    {
        $filepath = "./images/";
        if(fileDelete($filepath,$filename))
        {
            echo "success";
            header("Location: index.php");
            exit;
        }
        else echo "failed";
    }
}

输出 -

success
Warning: Cannot modify header information - headers already sent by (output started at C:\xampp\htdocs\pics\deletepic.php:31) in C:\xampp\htdocs\pics\deletepic.php on line 32