Solved

conversion from a byte to a signed byte

Posted on 2013-06-20
6
405 Views
Last Modified: 2013-06-20
hi - i'm using C#, VS2010 and .net 4. I have a line of code --

mesDataDisplay_WFG.graph.PlotYAppend((double)(Convert.ToSByte(HIDData[0])), xIncrement);

where the HIDData is typed as a byte array. I get an overflow exception saying that the value '254' is an overflow. I would have expected it to convert automatically to -2. it's not that I can't do the arithmetic to make it work, but I don't understand why it doesn't make the conversion.
thanks.
0
Comment
Question by:jdcoburn
6 Comments
 
LVL 75

Expert Comment

by:käµfm³d 👽
ID: 39264494
There is no such thing as a "signed" byte. Valid byte values are 0 to 255.

Screenshot
0
 
LVL 29

Expert Comment

by:anarki_jimbel
ID: 39264528
This is not quite correct:
http://msdn.microsoft.com/en-us/library/a7yfs6t2.aspx

Convert.ToSByte(Byte)

"Converts the value of the specified 8-bit unsigned integer to the equivalent 8-bit signed integer."

Throws OverflowException if value is greater than SByte.MaxValue (The value of this constant is 127; that is, hexadecimal 0x7F).
See http://msdn.microsoft.com/en-us/library/system.sbyte.maxvalue.aspx.
0
 
LVL 29

Accepted Solution

by:
anarki_jimbel earned 500 total points
ID: 39264544
Try:

            byte b = 254;
            sbyte sb = unchecked((sbyte)b);
            System.Diagnostics.Debug.WriteLine("byte = {0}; sbyte = {1}", b, sb);

Open in new window


Output:

byte = 254; sbyte = -2
0
DevOps Toolchain Recommendations

Read this Gartner Research Note and discover how your IT organization can automate and optimize DevOps processes using a toolchain architecture.

 
LVL 79

Expert Comment

by:David Johnson, CD, MVP
ID: 39264560
static void Main(string[] args)
        {
            UInt16[] numbers = { 127, 128, 65535, 65534 };
            Int16 output;
            Int16 counter;
            for (counter = 0; counter < 4; counter++)
            {
                output = unchecked((Int16)numbers[counter]);
                Console.WriteLine("Output = {0}", output);
            }
            Console.ReadLine();
        }

gives me the results
Output = 127
Output = 128
Output = -1
Output = -2

I run on a 64bit computer therefor int8 is not available.  If I change it to
Int16[] numbers = { 127, 128, 65535, 65534 };
the last 2 values are greater than maxint16
0
 

Author Closing Comment

by:jdcoburn
ID: 39264837
well done - this is exactly what I needed. the first comment was not only wrong, it was snooty.
thanks,
0
 
LVL 75

Expert Comment

by:käµfm³d 👽
ID: 39264856
I concede that it was incorrect--in terms of no sbyte, not in terms of the valid values for byte, but it wasn't intended to be snooty. (I'm honestly not certain what part of my statement could be considered "snooty.") I was thinking about the type incorrectly. Every other integral type in .NET that is signed is simply its name (e.g. Int16, Int32, Int64), and the unsigned equivalents all start with a "U" (e.g. UInt16, UInt32, UInt64). It was simply a flawed projection by me that you were stuck with byte since there was no "UByte". I completely overlooked that there was an sbyte.
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Host asp.net pages 5 26
Vb. Net application freezes 9 31
Finally almost got it 5 23
How useful is the free version of Selenium? 3 16
This article describes relatively difficult and non-obvious issues that are likely to arise when creating COM class in Visual Studio and deploying it by professional MSI-authoring tools. It is assumed that the reader is already familiar with the cla…
Performance in games development is paramount: every microsecond counts to be able to do everything in less than 33ms (aiming at 16ms). C# foreach statement is one of the worst performance killers, and here I explain why.
Video by: Mark
This lesson goes over how to construct ordered and unordered lists and how to create hyperlinks.
Both in life and business – not all partnerships are created equal. As the demand for cloud services increases, so do the number of self-proclaimed cloud partners. Asking the right questions up front in the partnership, will enable both parties …

863 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

21 Experts available now in Live!

Get 1:1 Help Now