Display PDF on browser

Use exit after readfile:

$filepath = 'your-path/demo.pdf';
header('Content-Type: application/pdf');
header(sprintf("Content-disposition: inline;filename=%s", basename($filepath)));

@readfile($filepath);
exit;

ps. @ before readfile it's used to suppress errors, maybe remove it in dev mode.

you can use PDF Merger library to achive your goals. Here is the link to original library (outdated). Prefer myokyawhtun fork which is maintained

and a sample code will be as following

include 'PDFMerger.php';
$pdf = new PDFMerger;
$pdf->addPDF('path_to_pdf/one.pdf', '1, 3, 4')  //include file1 - pages 1,3,4
    ->addPDF('path_to_pdf/two.pdf', '1-2')      //include file2 -  pages 1 to 2
    ->addPDF('path_to_pdf/three.pdf', 'all')    //include file3 - all pages
    ->merge('browser', 'test.pdf');  // OUTPUT : make sure you choose browser mode here.

Supported modes - browser, file, download and string.

---

Edit : As i can see you have tagged CI you can put PDFMerger.php in applications/libraries. and load it in autoload.php or in controller

and then can use it like $this->pdfmerger->addPDF() and merge() functions.

Instead of using

@readfile($file);

Use

echo file_get_contents($file);

Or ommit the @

$filePath="file path here";
$filename="file name here";
header('Content-type:application/pdf');
header('Content-disposition: inline; filename="'.$filename.'"');
header('content-Transfer-Encoding:binary');
header('Accept-Ranges:bytes');
@ readfile($filePath);

please try this code i hope it will working as i try.