C# BinaryWriter is Little Endian Because Microsoft Hates The Internet

Let's assume that you're developing the primary runtime class library for a programming language, and you need to write primitive types to a network connection. You've essentially got two options:

• Allow the application to specify the endianness of the data
• Require the application to use a particular endinanness.

The former allows developers more flexibility, but it means they have to think, and thinking is hard.

Let's assume that you've decided to not allow the user to specify the endianness of the data that the user is going to send over the wire easily. What endianness might you then choose for your developers? Might you choose the one that's officially called "Network Byte Order?"

Well, no. You're working on .NET and you work for Microsoft, so you'll use the opposite of that.

Now let's assume that you have a developer who's trying to do the right thing (where the right thing is not to start crying "Waaah, C# sucks, so you have to change the internet to support whatever Ballmer's got cooking"). You might try to make it easy for them to output data in network byte order. How might you do that?

By hiding the .NET equivalent of htonl and ntohl as static methods in System.Net.IPAddress, duh. Because that's obviously where you'd look when thinking of where to find binary data endian conversion routines. What in the world could be more logical or easy to find without StackOverflow?

Note: To be fair, it's entirely possible that Microsoft has not chosen little-endian by conscious decision, but is merely using host byte order. But for compatibility, Mono has to replicate this as little-endian-always. Which is going to be a lot of fun if and when Microsoft actually tries to port this to a new architecture.