Re: How do I store two int values into one DWORD, and then convert it to a 4 byte array? - C# Discussion Boards

Re: How do I store two int values into one DWORD, and then convert it to a 4 byte array?

8-Aug-11 5:08

Hi.

This does not seem to work.

It produces the following uint:

129098304

and I need 396398565

Thank you,
Stephen

PIEBALDconsult8-Aug-11 15:31

Re: How do I store two int values into one DWORD, and then convert it to a 4 byte array?

8-Aug-11 15:31

Why?

BobJanova7-Aug-11 23:12

Re: How do I store two int values into one DWORD, and then convert it to a 4 byte array?

7-Aug-11 23:12

BitConverter.GetBytes(a + 1000000*b)

stephen.darling8-Aug-11 4:45

Re: How do I store two int values into one DWORD, and then convert it to a 4 byte array?

8-Aug-11 4:45

Thank you,

Steve

stephen.darling8-Aug-11 5:28

Re: How do I store two int values into one DWORD, and then convert it to a 4 byte array?

8-Aug-11 5:28

Hi,

Sorry, this produces a different result than required.

uint val1 = 583;
uint val2 = 728439;

I should have 583728439, which sould be (in bytes) 0x22CAFD37.

Am I doing something wrong?

Thank you,
Stephen

BobJanova8-Aug-11 7:30

Re: How do I store two int values into one DWORD, and then convert it to a 4 byte array?

8-Aug-11 7:30

See below.

Matt Meyer8-Aug-11 6:55

Matt Meyer

8-Aug-11 6:55

You can combine them using division and modulo operations:

const uint shift = 1000000;
uint val1 = 539;
uint val2 = 666666;

// creat a combined value
uint combined = (val1 * shift) + val2;
// restore from the combined value
uint restore_val1 = combined / shift;
uint restore_val2 = combined % shift;

As for getting the byte array, you can use the BitConverter:

byte[] combined_bin = BitConverter.GetBytes(combined);

Re: How do I store two int values into one DWORD, and then convert it to a 4 byte array?

stephen.darling8-Aug-11 7:38

8-Aug-11 7:38

Thank you very much.

That works perfect.

Steve

Is this the same?

stephen.darling7-Aug-11 10:07

7-Aug-11 10:07

Hi.

The following function was taken from c++ code, and I have tried to adapt it for my c# code, however, I am not sure if it is doing the same thing?

The full c++ function is...

void ShowProdKey(unsigned char *ProdKey)
{
	unsigned int Val1, Val2;

	Val1 = *(unsigned int *)ProdKey;
	Val1 &= 0x7fffffff;
	Val1 >>= 1;

	Val2 = CheckDigit(Val1 % 1000000);
	Val1 /= 1000000;

	printf("Your product ID should be XXXXX-%.3u-%.7u-XXXXX.\n", Val1, Val2);
}

and my adapted function is the following (it works as in as far as it is producing a result which looks correct, but I am unsure if the changed part of the function is doing the same as in the above code)

void ShowProdKey(byte[] prodKey)
        {
            uint val1, val2;

            val1 = BitConverter.ToUInt32(prodKey, 0);

            val1 &= 0x7fffffff;
            val1 >>= 1;

            val2 = CheckDigit(val1 % 1000000);
            val1 /= 1000000;

            string output = ("");

            output = val1.ToString();
            output += val2.ToString();


            MessageBox.Show(output);

        }

So the part I changed was this in c++

Val1 = *(unsigned int *)ProdKey;

To this...

val1 = BitConverter.ToUInt32(prodKey, 0);

The output should be a double word formatted something like...

000 - 0000000

My version does produce a value like this, so I think it may be doing the same thing?

Also, how would I write code to reverse the function?
Or, in other words, the above function takes 4 bytes and produces a DWORD, which it formats into two unsigned ints...

How would I write a function that would take two unsigned ints, and produce a DWORD, and then encode that into 4 bytes, the reverse of the above function?

Thank you VERY much for your help...
Stephen

PIEBALDconsult7-Aug-11 10:20

7-Aug-11 10:20

stephen.darling wrote:
Val1 = *(unsigned int *)ProdKey;

Can probably be done with unsafe code.

stephen.darling wrote:
Val1 >>= 1;

Probably makes it non-reversible (except with a 50/50 probability of being correct).

stephen.darling wrote:
CheckDigit

What does that do?

What is it trying to do? It doesn't seem to use all the bits that are sent in.

stephen.darling7-Aug-11 10:33

7-Aug-11 10:33

Hi,

Well, using that function, if the 4 bytes are:

0x22CAFD37, the function should produce the following number:

583728439

Now, using the c++ version it works correct, but my c# version does not produce the correct value, it does produce a 9 digit number, but not that one.

However, if I try to use:

Val1 = *(unsigned int *)ProdKey;

in my c# version, it wont compile, so not sure if the code I changed is doing something else?

To answer what it is, let me explain...

My keygenerator generates the above 9 digit number, as a kind of product ID value, and encodes it into a 4 byte array to build part of a serial number..

When the serial number is entered into my application, the 4 bytes are decoded back into a dword, and the above function formats it into the 9 digits shown, and my app checks them,

It is working, and 9 digits are produced, but they are incorrect????

Also, how do I reverse the code to get two int values into one DWORD, and then encode it back into a 4 byte array?

Thank you,
Stephen

BobJanova7-Aug-11 23:10

7-Aug-11 23:10

The BitConverter code looks correct. (Just like a cast in C, though, it will give a different answer if the machine has the opposite endianness.) Your code is doing more than just that – what is CheckDigit doing?

stephen.darling8-Aug-11 4:44

8-Aug-11 4:44

Hi.

Thank you. So How do I check and/or fix the endian?

If it helps, the text I have says that it is stored in little endian byte order, and the following four bytes: 0x22CAFD37 should produce 583728439.

The checkdigit function then calculates and adds a checkdigit so that the above is then:

5837284392

here is the code for check digit...

XML

<pre>uint CheckDigit(uint val)
    {
        uint sum, copy;
        sum = 0;
        copy = val;
        while (copy !=0)
        {
            sum += copy % 10;
            copy /= 10;
        }
        return val * 10 + 7 - (sum % 7);
    }</pre>

thank you

BobJanova8-Aug-11 7:25

8-Aug-11 7:25

On my machine (Windows 32 bit) I'm getting the opposite order:

      $BitConverter:GetBytes(5)
(5 0 0 0)
      $BitConverter:GetBytes(583728439)
(55 253 202 34)
      {x: x:ToString "X2"}¨($BitConverter:GetBytes(583728439))
(37 FD CA 22)

This should be the same in C++, however.

(I can't so easily test the other way around, my toy language doesn't understand about bytes as a native type at the moment.)

stephen.darling8-Aug-11 7:40

How to delete some number in String format

8-Aug-11 7:40

OK,thank you.

I will keep trying on with this.

Steve

nassimnastaran7-Aug-11 9:50

7-Aug-11 9:50

Hi All !
myVal=1365 , and in the String.Format i want to get only Two last digit number(65) .
using with String.Format , any body help to this :

String.Format("{0:00}",myVal);

but the output is : 1365
Regards !

PIEBALDconsult7-Aug-11 9:52

7-Aug-11 9:52

I'd use mod (%) 100.

nassimnastaran7-Aug-11 9:55

7-Aug-11 9:55

thanks , but is it possible with String Format

PIEBALDconsult7-Aug-11 9:56

7-Aug-11 9:56

Not to my knowledge. Frown | :(

nassimnastaran7-Aug-11 10:01

7-Aug-11 10:01

in any case , Thanks !

Shameel7-Aug-11 23:37

Shameel

7-Aug-11 23:37

The string.Format method is used to get a string representation of an object in the specified format. It is not intended to change the value of its arguments. You can use

int m = n % 100;

to get the last two digits of the number. If at all you have to use strings to achieve the same answer, you can do this

string m = n.ToString().SubString(n.ToString().Length - 2);

nassimnastaran8-Aug-11 2:17

Who gets the priority to access when 2 users try to connect to?

8-Aug-11 2:17

thanks , it works !

Gali19787-Aug-11 3:49

Gali1978

7-Aug-11 3:49

if 2 users connect to access and run query that check the last number
increase this number and insert record to database.
Who gets the priority ?
why i see 2 duplicate records with the same number ?
thanks in advance

Re: Who gets the priority to access when 2 users try to connect to?

PIEBALDconsult7-Aug-11 5:46