play with integer numbers

[=?Utf-8?B?Y2hyaXNiZW4=?=]

Hi,

I try to use an integer to pass 4 kinds of information. Each kind may have 5
types. I plan to use an integer like 2034, while 2 0 3 4 are corresponding to
the type of each kind. I am wondering, what is the most efficient way to

1. update any of field, for example, changing from 2034 to 2134

2. grab the number (0 to 4) from any one of those field. for example,
immediately figure out my third kind is type 3 by reading 2034.

There are many ways of doing it. I am wondering whether there is a way (as
bitwise operations etc.) that I can use to do it most efficiently.

Thanks

Chris

[=?Utf-8?B?RmFtaWx5IFRyZWUgTWlrZQ==?=]

I cannot imagine the process of encoding and decoding the four values to a
four digit integer will better than simply passing the four values.

You won't be able to use bitwise operations, because it appears you are
using base 10 logic to build your integer. You would need to do integer
divisions and mods to split the int apart, or else split the string itself to
four single chararcter string to get an int.

"chrisben" wrote:

Hi,

I try to use an integer to pass 4 kinds of information. Each kind may have 5
types. I plan to use an integer like 2034, while 2 0 3 4 are corresponding to
the type of each kind. I am wondering, what is the most efficient way to

1. update any of field, for example, changing from 2034 to 2134

2. grab the number (0 to 4) from any one of those field. for example,
immediately figure out my third kind is type 3 by reading 2034.

There are many ways of doing it. I am wondering whether there is a way (as
bitwise operations etc.) that I can use to do it most efficiently.

Thanks

Chris

[=?Utf-8?B?TW9ydGVuIFdlbm5ldmlrIFtDIyBNVlBd?=]

"chrisben" wrote:

Hi,

I try to use an integer to pass 4 kinds of information. Each kind may have 5
types. I plan to use an integer like 2034, while 2 0 3 4 are corresponding to
the type of each kind. I am wondering, what is the most efficient way to

1. update any of field, for example, changing from 2034 to 2134

2. grab the number (0 to 4) from any one of those field. for example,
immediately figure out my third kind is type 3 by reading 2034.

There are many ways of doing it. I am wondering whether there is a way (as
bitwise operations etc.) that I can use to do it most efficiently.

Thanks

Chris

Hi Chris,

You can store many values inside an integer data type. Using bit
manipulation you can split the number into fields and work with the fields
and combine them to a number afterwards

int n = 123456789;

int field1 = n & 0xFF;
int field2 = (n >>= 8) & 0xFF;
int field3 = (n >>= 8) & 0xFF;
int field4 = n >>= 8;

int o = (field4 <<= 24) | (field3 <<= 16) | (field2 <<= 8) | field1;

The above code splits the integer into four equal 8 bit parts but you can
just as well use variable parts. Change the mask and bit shift positions as
needed.

You can also use the BitArray and BitVector32 classes meant for manipulating
values stored as bits inside a bigger data type. BitVector32 specifically
uses int32 as storage type.

--
Happy Coding!
Morten Wennevik [C# MVP]

[Peter Duniho]

On Fri, 17 Oct 2008 08:52:01 -0700, chrisben
<ch******@discussions.microsoft.comwrote:

Hi,

I try to use an integer to pass 4 kinds of information. Each kind may
have 5
types. I plan to use an integer like 2034, while 2 0 3 4 are
corresponding to
the type of each kind. I am wondering, what is the most efficient way to

1. update any of field, for example, changing from 2034 to 2134

2. grab the number (0 to 4) from any one of those field. for example,
immediately figure out my third kind is type 3 by reading 2034.

There are many ways of doing it. I am wondering whether there is a way
(as
bitwise operations etc.) that I can use to do it most efficiently.

I agree with FTM. You should probably rethink whether you really should
be compressing your data into a single int. For the vast majority of
applications, this sort of thing really isn't necessary. Memory and disk
space is cheap, and even bandwidth is pretty high these days. At most,
just use the smallest word size needed for the value that's possible. If
all your values are less than 256 (and it appears they are), then you can
put them in bytes instead of ints.

In fact, doing it that way will use the exact same amount of space, but
with much simpler code. It's essentially the same way to store the data
as Morten has suggested, but with much more readable code.

Pete

[Jeff Johnson]

"chrisben" <ch******@discussions.microsoft.comwrote in message
news:44**********************************@microsof t.com...

I try to use an integer to pass 4 kinds of information. Each kind may have
5
types. I plan to use an integer like 2034, while 2 0 3 4 are corresponding
to
the type of each kind. I am wondering, what is the most efficient way to

1. update any of field, for example, changing from 2034 to 2134

2. grab the number (0 to 4) from any one of those field. for example,
immediately figure out my third kind is type 3 by reading 2034.

There are many ways of doing it. I am wondering whether there is a way (as
bitwise operations etc.) that I can use to do it most efficiently.

You are a human being and this method of encoding works great for a human
being, but it's terrible for a computer. Computers do not see decimal
digits, they see binary digits. Since you have five potential values, you'll
need 3 bits to represent the each range (and you'll have 3 "wasted" values,
since 3 bits can hold 8 numbers: 0 - 7). In a 32-bit integer you'd have room
for 10 of these values (with 2 bits left over). You could apply masking and
bit shifting to get your values, but no matter what these numbers won't LOOK
like what you have above.

If you absolutely MUST use the format you indicated, you might as well just
start doing integer division by powers of 10 and then modding ( % ) to
extract each digit.

Or you could use the classes Morten mentioned.

[=?Utf-8?B?Y2hyaXNiZW4=?=]

Thank you guys. I was looking for the answer as Morten suggested. Since I
pass a lot of data through the network by the middleware, I tried to compress
the msg as small as possible. Maybe a little bit overdone. need to think
about it.
Thanks