Why C++ msgpack-c adds number 13 (0x0D) before number 10 (0x0A), but C# MessagePack-CSharp does not?

Question

I was trying to use MessagePack to serialize integers from 0 to 127 in C++ and in C# on Windows, but the results are not the same. msgpack-c inserts 0x0D between 0x09 and 0x0A, but MessagePack-CSharp does not. Why is that?

OS: Windows 10

IDE: Visual Studio 2019

C#

library:

https://github.com/neuecc/MessagePack-CSharp

code:

using System.Collections.Generic;
using System.IO;

class Program
{
    static void Main(string[] args)
    {
        using (FileStream fileStream = new FileStream("CSharp.msgpack", FileMode.Create, FileAccess.Write))
        {
            List<int> list = new List<int>();

            for (int i = 0; i < 128; ++i)
            {
                list.Add(i);
            }

            MessagePackSerializer.Serialize(fileStream, list);
        }
    }
}

result:

C++

library:

https://github.com/msgpack/msgpack-c

code:

#include <msgpack.hpp>
#include <vector>
#include <iostream>
#include <fstream>

int main(void)
{
    std::ofstream OutputFileStream;

    std::vector<int> list;

    for (int i = 0; i < 128; ++i)
    {
        list.push_back(i);
    }

    OutputFileStream.open("Cpp.msgpack");

    msgpack::pack(OutputFileStream, list);

    OutputFileStream.close();
}

result:

But if I have a list of 128 integers serialized in a binary file, the result should be the same, should it not? — Jinjinov, May 13 '19 at 15:24
Oh. Well my guess is that the two pieces of software aren't guaranteed to be compatible with each other. — Robert Harvey, May 13 '19 at 15:25
If you are serialising into a binary file, then you need to open the file in binary mode. — Richard Critten, May 13 '19 at 15:26
@RichardCritten: Good catch, but why would a text stream assume something about the size of your lines? — Robert Harvey, May 13 '19 at 15:27
@RobertHarvey the perennial Unix vs MS-Windows line-ending issue. — Richard Critten, May 13 '19 at 15:28

score 5 · Accepted Answer · answered May 13 '19 at 15:34

Since you open the file in c++ in text mode then every \n (ASCII 10) will have \r (ASCII 13) prepended if it doesn’t exist on Windows. You need to open the file in binary mode for this to not happen.

OutputFileStream.open("Cpp.msgpack", std::ofstream::binary);

Why C++ msgpack-c adds number 13 (0x0D) before number 10 (0x0A), but C# MessagePack-CSharp does not?

1 Answers1