C#, read structures from binary file

Question

I want to read structures from binary. In C++ I would do it like this:

stream.read((char*)&someStruct, sizeof(someStruct));

Is there a similar way in C#? The BinaryReader only works for built-in types. In .NET 4 there is a MemoryMappedViewAccessor. It provides methods like Read<T> which seems to be what I want, except that I manually have to keep track of where in the file I want to read. Is there a better way?

Answer 1

public static class StreamExtensions
{
    public static T ReadStruct<T>(this Stream stream) where T : struct
    {
        var sz = Marshal.SizeOf(typeof(T));
        var buffer = new byte[sz];
        stream.Read(buffer, 0, sz);
        var pinnedBuffer = GCHandle.Alloc(buffer, GCHandleType.Pinned);
        var structure = (T) Marshal.PtrToStructure(
            pinnedBuffer.AddrOfPinnedObject(), typeof(T));
        pinnedBuffer.Free();
        return structure;
    }
}

You need to ensure your struct is declared with [StructLayout] and possibly [FieldOffset] annotations to match the binary layout in the file

EDIT:

Usage:

SomeStruct s = stream.ReadStruct<SomeStruct>();