MemoryStream to sbyte[]

Question

I'm still trying to add a jpeg image to a person in Open LDAP, using Novell's c# libraries:

There is a constructor for Novell.Directory.Ldap.LdapAttribute the with the following signature:

public LdapAttribute(string attrName, sbyte[] attrBytes)

So, I plan to use this one. But, how to convert a jpeg image from a MemoreyStream to sbyte[]?

MemoryStream.ToArray()

method returns byte[] and I don't know how to do it.

score 3 · Accepted Answer · answered May 30 '14 at 14:02

3

You can convert the array like this:

Array.ConvertAll(bytes, b => (sbyte)b)

answered May 30 '14 at 14:02

SLaks

2

Much better than my `MemoryStream.ToArray().Select(a=>(sbyte)a).ToArray()` idea I was going to post. – Scott Chamberlain May 30 '14 at 14:03
Thanks for your answer. But in the original array there are values greater than 127. What will happen? Will cause errors? The conversion won't make the image unreadable? – Oscar May 30 '14 at 14:04
1

@Oscar: They will be viewed as negative numbers; the underlying bytes will not change. This must be done in an `unchecked` context. – SLaks May 30 '14 at 14:06
1

Actually, the C# `byte` is unsigned - http://msdn.microsoft.com/en-us/library/ms228360%28v=vs.90%29.aspx – David Crowell May 30 '14 at 14:17
@DavidCrowell: That's exactly why he's asking this. – SLaks May 30 '14 at 14:18

score 1 · Answer 2 · edited May 23 '17 at 12:11

1

On the CLR you can constant-time convert a byte[] to an sbyte[]. See my previous answer on this little-known trick.

(sbyte[])(object)MemoryStream.ToArray(); //compiles and runs

edited May 23 '17 at 12:11

Community

answered May 30 '14 at 14:26

usr

2 Answers2