smallest type

[Bob]

Hi,
I have a newbie question. What is the smallest type object size? I am
doing some calculation with individual bits and want to minimize memory
usage. I though bool might do it but it seems like each bool is a
byte, instead of a bit. Is bool the smallest possible type?

Thanks,
Bob

[Dave Sexton]

Hi Bob,

Normally byte is used as the smallest integral data type.

--
Dave Sexton
http://davesexton.com/blog
http://www.codeplex.com/DocProject (Sandcastle in VS IDE)

"Bob" <bs********@yah oo.comwrote in message
news:11******** **************@ m58g2000cwm.goo glegroups.com.. .

Hi,
I have a newbie question. What is the smallest type object size? I am
doing some calculation with individual bits and want to minimize memory
usage. I though bool might do it but it seems like each bool is a
byte, instead of a bit. Is bool the smallest possible type?

Thanks,
Bob

[=?ISO-8859-1?Q?Arne_Vajh=F8j?=]

Bob wrote:

I have a newbie question. What is the smallest type object size? I am
doing some calculation with individual bits and want to minimize memory
usage. I though bool might do it but it seems like each bool is a
byte, instead of a bit. Is bool the smallest possible type?

If speed is important use byte else you can try the
System.Collecti ons.BitArray class.

Arne

[Dave Sexton]

In that case, BitVector32 is another alternative if you need to use flags or
small integers, "but it has the memory and performance overhead that a class
instance requires. In contrast [to BitArray], a BitVector32 uses only 32
bits" [1].

[1] BitVector32 Structure
http://msdn2.microsoft.com/en-us/lib...tvector32.aspx

--
Dave Sexton
http://davesexton.com/blog
http://www.codeplex.com/DocProject (Sandcastle in VS IDE)

"Arne Vajhøj" <ar**@vajhoej.d kwrote in message
news:45******** *************** @news.sunsite.d k...

Bob wrote:

>I have a newbie question. What is the smallest type object size? I am
doing some calculation with individual bits and want to minimize memory
usage. I though bool might do it but it seems like each bool is a
byte, instead of a bit. Is bool the smallest possible type?

If speed is important use byte else you can try the
System.Collecti ons.BitArray class.

Arne

[Bob]

Thanks for all the quick replies. By use byte, do you mean that an
byte[] where all the entries are either 0 or 1 will perform faster than
a similarly size bool[]?

Thanks,
Bob

On Jan 24, 9:27 pm, Arne Vajhøj <a...@vajhoej.d kwrote:

Bob wrote:

I have a newbie question. What is the smallest type object size? I am
doing some calculation with individual bits and want to minimize memory
usage. I though bool might do it but it seems like each bool is a
byte, instead of a bit. Is bool the smallest possible type?If speed isimportant use byte else you can try the

System.Collecti ons.BitArray class.

Arne

[Mattias Sjögren]

>By use byte, do you mean that an

>byte[] where all the entries are either 0 or 1 will perform faster than
a similarly size bool[]?

I think they will perform pretty much the same, since bytes and bools
are usually treated the same way by the runtime. Both types are 1
byte.
Mattias

--
Mattias Sjögren [C# MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.

[Willy Denoyette [MVP]]

"Bob" <bs********@yah oo.comwrote in message
news:11******** **************@ m58g2000cwm.goo glegroups.com.. .

Hi,
I have a newbie question. What is the smallest type object size? I am
doing some calculation with individual bits and want to minimize memory
usage. I though bool might do it but it seems like each bool is a
byte, instead of a bit. Is bool the smallest possible type?

Thanks,
Bob

It depends on what you mean with "object" size, the smallest *Reference type* size type is
an int.
byte b = 1;
object o = b;
here, o will take 12 bytes (on X86), 8 bytes object header plus 4 bytes for the byte value.

If you mean primitive type size, then by definition the smallest type is a byte, but again
it highly depends on where and how they are allocated.

void Foo()
{
byte b;
int i;
...

In above sample, both b and i will be stored on the stack, both i and b will occupy a slot
on the stack( Int32 on x86).
void Foo()
{
byte b;
int i;
byte b2;
byte b3,
byte b4;

In above, the four bytes will occupy a single slot (4 bytes on X86) just like i. so here the
same amount of memory is used as the previous sample.

class Foo{
byte b;
int i;
byte b2;
byte b3,
byte b4;
}

class Bar {
byte b;
int i;
}

Same here, An instance of Foo or Bar will occupy the same amount of memory, that is, 8
bytes header plus 8 bytes for the data members.
Conclusion, it makes little sense to use a smaller value than an int if you can't combine a
number of these small integer values.

Willy.

[Fabio Z]

"Mattias Sjögren" <ma************ ********@mvps.o rgha scritto nel messaggio

I think they will perform pretty much the same, since bytes and bools
are usually treated the same way by the runtime. Both types are 1
byte.

mmm... I know that in .net a bool is a 4 bytes, and used as a Int32 in
compiled IL for compares.
And for performances a 4 bytes on a 32bits architecture is best over each
other lengths.
If the aim is a small flags data type use an enum x : byte

Personally I will avoid these thoughts about memory allocation in .Net, sice
it is fully managed by the famework and the garbage collector (also the data
in the taskmanager about .net apps are all lies).

[Mattias Sjögren]

>mmm... I know that in .net a bool is a 4 bytes

You do eh? And yet Console.WriteLi ne(sizeof(bool) ) prints 1.
Mattias

--
Mattias Sjögren [C# MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.

[Fabio]

"Mattias Sjögren" <ma************ ********@mvps.o rgha scritto nel messaggio

>

>>mmm... I know that in .net a bool is a 4 bytes

You do eh? And yet Console.WriteLi ne(sizeof(bool) ) prints 1.

And my IL says that bool x = true is

L_0001: ldc.i4.1

i4 stays for Int32.
1 stays for the "true" value (0 is false).

And now? ;)