我如何在php while循环中连接多个pdf文件

Question

示例代码 - 我使用了fpdf和pdf merge，当我运行此代码时，第一个和最后一个文件正在连接file1和file10。我想要连接所有文件

$i=1;
include "Barcode39.php";
include 'PDFMerger/PDFMerger.php';

while($result=mysqli_fetch_array($res))
{

ob_start();
require_once('fpdf17/fpdf.php');
$pdf=new FPDF('L','mm',array(297,210));
$pdf->AddPage();
$pdf->Line(147.5,5,147.5,205); 
$pdf->Line(149.5,5,149.5,205);
$pdf->Line(6.8,5,6.8,205); 
$pdf->Line(291,5,291,205); 
$pdf->SetLineWidth(0.3);
$pdf->Line(6.8,25,148.5-1,25);
$pdf->Line(6.8,5,148.5-1,5);
$pdf->Line(6.8,205,148.5-1,205);
$pdf->Line(149.5,5,297-6.5,5);
$pdf->Line(149.5,205,297-6.5,205);
$pdf->SetLineWidth(0.3);
$pdf->Line(149.5,25,297-6.5,25);
$pdf->Line(6.8,33,148.5-1,33);
$pdf->Line(149.5,33,297-6.5,33);
$pdf->Line(6.8,125,148.5-1,125);
$pdf->Line(149.5,125,297-6.5,125);
$pdf->Line(6.8,131,148.5-1,131);
$pdf->Line(6.8,137,148.5-1,137);
$pdf->Line(149.5,131,297-6.5,131);
$pdf->Line(149.5,137,297-6.5,137);
$file_contents = $pdf->Output($file."shipexpresslabel.pdf",'S');
$temp_file='pdf/critica_shiplabel.pdf';  
$new_file='pdf/critica_shiplabel1'.$i.'.pdf'; 
file_put_contents($new_file, $file_contents);    
$pdf = new PDFMerger;
$pdf->addPDF($temp_file, '1')
    ->addPDF($new_file, '1')
    ->merge('file',$temp_file);

ob_end_flush(); 
$i=$i+1;

}