How o convert byte array any to its original file when downloading the ant type of file like pdf, excel, png, jpg like that

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how o convert byte array any to its original file when downloading the any type of file like
pdf, excel,png,jpg like that

What I have tried:

C#

string fileName = "file";

byte[] pdfasBytes = Encoding.ASCII.GetBytes(file);
Response.Clear();
MemoryStream ms = new MemoryStream(pdfasBytes);
Response.ContentType = "application/pdf";
Response.Headers.Add("content-disposition", "attachment;filename=" + fileName);
// Response.OutputStream.Write(ms.GetBuffer(), 0, ms.GetBuffer().Length);
Response.Buffer = true;
ms.WriteTo(Response.OutputStream);
Response.Flush();
Response.End();

return file;

Posted 9-Mar-21 20:08pm

Prakash kumar mumbai

Updated 10-Mar-21 5:52am

Patrice T

v3

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OriginalGriff · Answer 1 · 2021-03-09T20:44:00

All files are byte arrays: that is all that a hard disk knows how to store.
It's the organisation of the data in those bytes that controls how an app works with it: a text file will be limited to just text characters rather than the "whole byte" value; a BMP file will be bytes starting with the characters "BM"; and EXE file is bytes starting with "MZ"; a CSV file is a text file with strings separated by commas; a DOCX file is a ZIP file with a different extension that contains other files and so on.

Basically, to return it to it's original file, all it needs is the right file name and extension - the extension controls which apps will open it by default, but doesn't change the actual data in the byte stream.

Richard Deeming · Answer 2 · 2021-03-10T05:00:00

Quote:

C#

string fileName = "file";
byte[] pdfasBytes = Encoding.ASCII.GetBytes(file);

Well, there's your problem. You're not reading any bytes from the specified file; you're taking the string "file" and getting an array of ASCII code-points representing the characters in that string.

The simplest option is to throw your code away and use the Response.TransmitFile[^] method instead:

C#

string virtualPath = "~/downloads/your-file.pdf";
string physicalPath = Server.MapPath(virtualPath);
Response.ContentType = "application/pdf";
Response.Headers.Add("content-disposition", "attachment;filename=" + Path.GetFileName(physicalPath));
Response.TransmitFile(physicalPath);

If you really want to read the file into memory first, then you'll need to actually read the file:

C#

string virtualPath = "~/downloads/your-file.pdf";
string physicalPath = Server.MapPath(virtualPath);
byte[] pdfasBytes = System.IO.File.ReadAllBytes(physicalPath);

NB: This is horribly inefficient. Every request is going to end up storing the entire contents of the file in memory twice - once for your byte array, and once for the buffered response. Your server will very quickly run out of memory.

How o convert byte array any to its original file when downloading the ant type of file like pdf, excel, png, jpg like that

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