Where am I going wrong?

Archive
1

Hi,

Just trying to get the PermanentUserKey to work on my USBizi device (FW Ver 4.1.8.0) and am creating some stub test code…

Having some real problems with the following code:

Guid g = Guid.NewGuid();
byte[] b = new byte[Configuration.PermanentUserKey.KeyLength];
b = g.ToByteArray();
char[] c = new char[Configuration.PermanentUserKey.KeyLength];
c = Encoding.UTF8.GetChars(b);
string s = new string(c);
return s;

No matter what I do I get a “Exception was thrown: System.Exception” on the line “c = Encoding.UTF8.GetChars(b);”

What have I missed? What am I doing wrong?

Thanks in advance,

Andy

2

Not all elements of your byte array result in printable characters. A GUID is a series of numbers, and ToByteArray returns the byte values of the numbers, not the printable characters that represent them. Notice that a GUID has 32 characters, while Guid.ToByteArray results in a byte array of 16 elements.

Also note:


Guid g = Guid.NewGuid();
byte[] b = new byte[Configuration.PermanentUserKey.KeyLength];
b = g.ToByteArray();
char[] c = new char[Configuration.PermanentUserKey.KeyLength];
c = Encoding.UTF8.GetChars(b);
string s = new string(c);
return s;

It is unnecessary to initialize b on the second line, and c on the fourth line, as neither Guid.ToByteArray() nor Encoding.UTF8.GetChars() copies the result into your array, but rather returns a new array.

3

I don’t have hardware on me to test. What does the progression of your GUID to Byte to Char look like?

Your first byte in b is actually decimal 180. I don’t think this is a valid UTF-8 character and GetChars is barfing at it.

have you tried just using g.ToString() and make the object to the work for you ?

1 Like
4

Hi guys,

Many thanks for the responses.

I had completely forgotten that the numbers were byte values and not actual characters! Too many late nights working on my project.

I knew I didn’t need to initialize on each line separately but when I was trying to find the cause of the problem I always separate out compound statements to find out which bit I have broken.

Many thanks again,

Andy