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How about a Nibble etc.

Gabe
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Shimmy Weitzhandler
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    BitOperations: http://www.blackwasp.co.uk/CSharpLogicalBitwiseOps.aspx –  Jul 09 '10 at 14:45
  • youre welcome. :) Its not a .NET data-type but it will allow you to manipulate the bits within a byte. You mentioned bools, you might also consider this helpful: Bit Fields - http://en.wikipedia.org/wiki/Bit_field –  Jul 10 '10 at 22:10

3 Answers3

16

No. Even if you have an array of Booleans, I believe they're specified to take up one byte each.

Of course you can define your own data types which have fewer than 256 valid values (like Boolean does) but you can't make it take up less than a byte in memory.

As LBushkin pointed out, there are types such as BitArray and BitVector32 which effectively pack multiple bits efficiently - you could write your own NybbleArray type if you wanted.

Jon Skeet
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  • I just took a look into the reflected BitArray, it's just a Boolean array with some functionality, for performance and portability it's not the best idea. – Shimmy Weitzhandler Jul 09 '10 at 14:54
  • @Shimmy: Hmm... it's possible that I'm wrong about the space taken up by a boolean array, of course... – Jon Skeet Jul 09 '10 at 15:04
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    @Shimmy: I don't think that's correct. Looking at the reflected code myself, I see it is implemented as an `int[]` array, with each `int` value serving as its own packed group of bits. – Dan Tao Jul 09 '10 at 15:12
  • @Dan, right, so anyway, it's definitely larger than a single Byte implementation (at least 4 bytes), so conclusion is, if you want to implement a Nibble, then it should probably be implemented with underlying Byte or SByte for best performance capabilities (don't forget it's a value type), or if you need it to play with single Nibbles, then I would better suggest to use the existing BitArray or BitConverter shared (static) methods or implement another shared class with your own functionality, or just embed it all in your byte-implemented Nibble structure, which is what I am going to do.. – Shimmy Weitzhandler Jul 10 '10 at 19:09
  • @Shimmy: I only meant to point out that it's designed in a way that makes sense -- i.e., what you would expect from a name like `BitArray` -- as opposed to "a Boolean array" as you described it, which would make it a pretty pointless data structure. As for what makes the most sense for performance capabilities, I'd say that depends entirely on your needs. Yes, if you want exactly 8 bits in the form of an immutable struct then sure, a `byte` makes sense. If you want 32 bits, I'd say an `int` makes more sense than 4 `byte`s. `BitArray` is mutable and intended to be used as such. – Dan Tao Jul 10 '10 at 21:29
  • @Shimmy: In any case, if your intention is specifically to create a data type that is *smaller* than a `byte`, the purpose of these answers is to point out that this isn't possible; you can only store data smaller than 1 `byte` if you break up existing structures (`byte`, `int`, or otherwise) in such a way that they represent multiple pieces of information. – Dan Tao Jul 10 '10 at 21:32
  • Right, but I want portable immutable objects that are less than a byte and not grouped, I guess I will simply use implementation of a Byte wrapper and that's it, cuz that's the smallest amount possible (in memory). thanks. – Shimmy Weitzhandler Jul 10 '10 at 21:44
  • Is there a way to generate a compiler error if I try to set for the nibble any value higher than 0xF? – Shimmy Weitzhandler Jul 22 '10 at 10:50
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    @Shimmy: No, I don't believe so. – Jon Skeet Jul 22 '10 at 11:49
  • @JonSkeet, gonna extend this conversation even more :) Anyway, I'm now working on a project that handles with binaries, and I thought about implementing a Nibble data-type. I copied the reflected code from System.Byte and made all the adaptions. Now, my question is, is there a way to instruct it like byte, i.e. `Nibble n = 0x7F;`? – Shimmy Weitzhandler May 13 '13 at 16:28
  • @Shimmy: This should be asked as a separate question. – Jon Skeet May 13 '13 at 16:58
  • @JonSkeet Actually I think I already found the answer. The compiler resolves this automatically. – Shimmy Weitzhandler May 13 '13 at 17:01
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There's no native data-type smaller than byte, however if you want to store and manipulate a group of packed bits, you can use BitVector32 or BitArray.

LBushkin
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1

No, byte is the smallest.

This may be helpful: How can you nibble (nybble) bytes in C#?

Community
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Mandelbrot
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  • Less memory? No. Fewer possible values? Yes. If you are trying to implement a Nibble type then the best way would be to either use a BitArray/BitVector as previously mentioned or to use bitmasking on bytes. – Mandelbrot Jul 09 '10 at 15:12