Simple example of php header() function

// The result is wrong
// There is already output before calling header()
header('Location: url');
?>

Two: Disable browser cache

header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
header("Cache-Control: no-cache");
header("Pragma: no-cache") ;

Three: Prompt to save a generated PDF file (the Content-Disposition header is used to provide a recommended file name and force the browser to display a save dialog box):

header("Content-type:application/pdf");
// The file will be called downloaded.pdf
 header("Content-Disposition:attachment;filename='downloaded.pdf'");
// The PDF source is in original.pdf
readfile("original.pdf");
? >

Four: Let the visitor's browser display a 404 prompt.

//404 not found
header("Status: 404 Not Found");
?>