这句代码怎么修改成PHP语句

Question

if username<>"" then
response.redirect "admin.asp"end if

Answer 1

if($username != '') {
   header('location: admin.asp');
}

Answer 2

if(!username!="")
{
headf("Location:admin.php");
}

Answer 3

if ($username!="")
  header(loction,"admin.php";
end if
if ($username!="")
  echo "<script>window.href='admin.php'</script>";
end if

Answer 4

if($username != '') 
{
header('location: admin.asp');
}

Answer 5

if ($username!="")
  echo "<script>window.href='admin.php'</script>";
end if