[Const-me]

I think C# standard library is better. You can do same unsafe code as in C, SafeBuffer.AcquirePointer method then directly access the memory. Or you can do safer and slightly slower by calling Read or Write methods of MemoryMappedViewAccessor.

All these methods are in the standard library, i.e. they work on all platforms. The C code is specific to POSIX; Windows supports memory mapped files too but the APIs are quite different.

[SvenL]

I think you don’t need to be unsafe, they have normal API for it.

https://learn.microsoft.com/en-us/dotnet/standard/io/memory-...

[Const-me]

Indeed, but these normal APIs have runtime costs for bounds checking. For some use cases, unsafe can be better. For instance, last time I used a memory-mapped file was for a large immutable Bloom filter. I knew the file should be exactly 4GB, validated that in the constructor, then when testing 12 bits from random location of the mapped file on each query, I opted for unsafe codes.