Byte array to string and back - wrong numbers! (from C# to C++)

[mjaaland]

Hi, I hope someone can help me out with this one!


Step 1: I get a struct from unmanaged code looking like this.
public unsafe struct KEY
{
public UInt16 idkey_len;
public byte* idkey;

}

I get the struct after unmanaged code has filled it with values, I can not change the unmanaged code. The byte * idkey indicates the start of a key I want to store, and the indkey_len is the length.

I observe through debugger that the first value is 96.... (where the pointer poitns to), and the length is 21.



Step 2: I work in C#, so I want to store this using other data structures.

byte[] idKey = new byte[key.idkey_len];
for (i = 0; i < idKey.Length; i++)
idKey[i] = *(key.idkey + i);

Debugging show that the resulting byte array begins with { 96, 0, 0...}, this is good, 9600 was above! Lenth of the array is 21 too.



Step 3:
I convert it to a string and store it in a .txt

foreach (byte b in idKey)
textwriter.Write(b);

The result begins with 9600..... Still good, the original started with 9600 as mentioned. There are 52 numbers in total.



Step 4: NOW it messes up. I want to load this and convert it back to the original struct, so first I read the numbers as a string, and I make a byte array out of it.
I use this for conversion:

System.Text.ASCIIEncoding encoding = new System.Text.ASCIIEncoding();
return encoding.GetBytes(str);

The resulting byte array have totally different numbers, respectively { 57, 54, 48 48... } and the length, well, I just set it to 21 cause I didn't know what else I could do.

In order to process it right I have to be able to reconstruct the struct mentioned in step one. That is, a byte pointer to the start of the whole thing! I don't have a way to come around it, as I said I cannot change the unmanaged code.

Please, I would GREATLY appreciate any help.

all the best
Bendik Mjaaland

[Plater]

0x00 is not a valid string byte and will be removed when you do string conversions. The same applies for many other byte values.
If you really want them stored as a string, store them as a HEX string:
"96 00 00 " etc

{ 57, 54, 48 48... } IS the byte values for "9600".

[mjaaland]

Thanks for answering!

But with hex string, will that really help me out? I want the result of a byte string with values {96, 0, 0, ....}, not {96, 00,....}

I am sure you know what you are talking about, if you could be more precise to someone a bit less experienced I would really appreciate it :).

PS! I also read about Base64 conversion of some kind, but when I tried Convert.FromBase64String (or something) I got a formaterror, supposedly the length of the string must be fixed to an even number of 8! Ideas?

Thank you

[Plater]

Ok so we need to clear things up.
You receive these byte values:
0x96 0x00 0x00
Correct?

And you wish to save them as a textual string?