managed c++ .NET extract file from resource, wrong file size

Question

Hi im trying to extract a file from my embedded resource but the issue is that the file size is not correct, it should be around 3500KB but it comes out as 5850KB or so.

            Assembly ^myAssembly = Assembly::GetExecutingAssembly();
        Stream ^myStream = myAssembly->GetManifestResourceStream("cool.exe");
        FileStream^ fs = gcnew FileStream("cool.exe",FileMode::Append,FileAccess::Write,FileShare::Write);
        StreamReader^ Reader = gcnew StreamReader(myStream);
        StreamWriter^ Writer = gcnew StreamWriter(fs);
        Writer->Write(Reader->ReadToEnd());
        fs->Close();

This is the edited one:

Assembly ^myAssembly = Assembly::GetExecutingAssembly();
        Stream ^myStream = myAssembly->GetManifestResourceStream("cool.exe");
        FileStream^ fs = gcnew FileStream("cool.exe",FileMode::Append,FileAccess::Write,FileShare::Write);
        StreamReader^ Reader = gcnew StreamReader(myStream);
        StreamWriter^ Writer = gcnew StreamWriter(fs);
        //Writer->Write(Reader->ReadToEnd());

        array<Byte^>^ buffer = gcnew array<Byte^>(256);

        while (true)
        {

            int read = Reader->Read(buffer,0,buffer->Length);
            if(read <= 0)
            {
                return;
            }
            Writer->Write(buffer,0,read);
        }

        fs->Close();

SOLOUTION

public: static void CopyStream(Stream^ input, Stream^ output) 
        {     

            array<Byte>^ buffer = gcnew array<Byte>(32768);

            long TempPos = input->Position; 

            while (true)         
            {         
                int read = input->Read(buffer, 0, buffer->Length);         
                if (read <= 0) break;         
                output->Write (buffer, 0, read);     
            }     
            input->Position = TempPos;// or you make Position = 0 to set it at the start 
        }

Then to use it:

Assembly ^myAssembly = Assembly::GetExecutingAssembly();
        Stream ^myStream = myAssembly->GetManifestResourceStream("cool.exe");
        FileStream^ fs = gcnew FileStream("cool.exe",FileMode::Append,FileAccess::Write,FileShare::Write);

        CopyStream(myStream,fs);
        fs->Close();

This will make the correct file and correct file size =)

BTW, if you're using .Net 4.0, you can just call `Stream.CopyTo`. — SLaks, Jul 24 '11 at 20:04

score 2 · Accepted Answer · answered Jul 24 '11 at 16:29

2

Binary data isn't text.

The StreamReader is converting your data to UTF8, which isn't what you want.
You need to copy the raw bytes by calling Write and Read.

answered Jul 24 '11 at 16:29

SLaks

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could you link me to some documentation? Would I have to use BinaryWriter? – cccru Jul 24 '11 at 17:27
No. Just call `Read()` until it reads `0`, and `Write()` each block that you read. http://www.google.com/search?q=.net+copy+stream&ie=UTF-8 – SLaks Jul 24 '11 at 17:39
Ok i edited my post, am i going in the right direction? I am getting 1 error: Error 1 error C2664: 'void System::IO::TextWriter::Write(cli::array ^,int,int)' : cannot convert parameter 1 from 'cli::array ^' to 'cli::array ^' – cccru Jul 24 '11 at 17:54
You aren't dealing with text; you cannot use a `StreamWriter`. You need to write directly to the stream. http://stackoverflow.com/questions/230128/best-way-to-copy-between-two-stream-instances-c – SLaks Jul 24 '11 at 18:07
Ah ok so i used Stream instead and I still end up with the same error as above. – cccru Jul 24 '11 at 19:31

managed c++ .NET extract file from resource, wrong file size

1 Answers1