How to Merge two memory streams containing PDF file's data into one

Question

I am trying to read two PDF files into two memory streams and then return a stream that will have both stream's data. But I don't seem to understand what's wrong with my code.

Sample Code:

string file1Path = "Sampl1.pdf";
string file2Path = "Sample2.pdf";
MemoryStream stream1 = new MemoryStream(File.ReadAllBytes(file1Path));
MemoryStream stream2 = new MemoryStream(File.ReadAllBytes(file2Path));
stream1.Position = 0;
stream1.Copyto(stream2);
return stream2;   /*supposed to be containing data of both stream1 and stream2 but contains data of stream1 only*/  

Answer 1

It appears in case of PDF files, the merging of memorystreams is not the same as with .txt files. For PDF, you need to use some .dll as I used iTextSharp.dll (available under the AGPL license) and then combine them using this library's functions as follows:

MemoryStream finalStream = new MemoryStream();
PdfCopyFields copy = new PdfCopyFields(finalStream);
string file1Path = "Sample1.pdf";
string file2Path = "Sample2.pdf";

var ms1 = new MemoryStream(File.ReadAllBytes(file1Path));
ms1.Position = 0;
copy.AddDocument(new PdfReader(ms1));
ms1.Dispose();

var ms2 = new MemoryStream(File.ReadAllBytes(file2Path));
ms2.Position = 0;
copy.AddDocument(new PdfReader(ms2));
ms2.Dispose();
copy.Close();

finalStream contains the merged pdf of both ms1 and ms2.