Solved

Xor in .NET, vs "^" in Javascript

Posted on 2004-09-16
8
909 Views
Last Modified: 2012-06-21
When I do this in javascript:

3988292384 ^ 0

I get this:

-306674912

HOWEVER, in VB.net, when I evaluate 3988292384 Xor 0, I get 3988292384.

What's going on?
0
Comment
Question by:electricstory
  • 4
  • 4
8 Comments
 
LVL 4

Expert Comment

by:vigrid
ID: 12076695
Maybe a hexadecimal mode will help:

3988292384 is 0x00000000EDB88320
-306674912 is 0xFFFFFFFFEDB88320

So JavaScript seems to convert the number to 64-bit form and do something weird about it, while VB does not.

HTH
0
 

Author Comment

by:electricstory
ID: 12076789
Very good observation! If you can figure out how I can emulate the behavior in .NET, you get all the points. (I don't deal much with bitwise and hex operations, so I'm a bit out of my depth.)
0
 
LVL 4

Expert Comment

by:vigrid
ID: 12076957
Do you need to implement the JS behavior in .NET, or to implement .NET behavior in JS? Just to be sure before I code :)
0
The New “Normal” in Modern Enterprise Operations

DevOps for the modern enterprise offers many benefits — increased agility, productivity, and more, but digital transformation isn’t easy, especially if you’re not addressing the right issues. Register for the webinar to dive into the “new normal” for enterprise modern ops.

 

Author Comment

by:electricstory
ID: 12077038
The js behavior in .NET. I'm converting javascript code. Thanks!
0
 
LVL 4

Expert Comment

by:vigrid
ID: 12077104
Sorry, I seem to have only the C# compiler installed on this machine. If you would go for the C# code, I could try and implement it in C#, but I can't do it in VB.NET right now.
0
 

Author Comment

by:electricstory
ID: 12077154
C# is fine.
0
 
LVL 4

Accepted Solution

by:
vigrid earned 500 total points
ID: 12077343
OK, I think I know exactly what happened (didn't realize that until started coding)

the value 3988292384 (dec) is 0xEDB88320 (hex). It's greater than 0x7FFFFFFF, so it should be considered negative value. The normal integer (31 bits value + 1 bit sign) type can't hold this value, however an unsigned integer (32 bits value) type can. So in order to preserve the sign of your input, JavaScript is treating this variable as a long (63 bits + 1 bit sign = 0xFFFFFFFFEDB88320). The way JavaScript performs the XOR operation seems to be weird. Order of value type conversions is not intuitive at the first glance. The XOR operation took 2 agruments of different types - the big number (64 bits) and zero (32 bits) and performed the XOR-ing only on the lower 32 bits, leaving the rest untact.

I don't know how do you want to use the XOR in your code, but I think that the System.Collections.BitArray can help you with the Xor method. I wouldn't emulate the misbehaving code in order to translate from one language to another...
0
 

Author Comment

by:electricstory
ID: 12077405
Okay, well that helps a good deal. Thanks!
0

Featured Post

Webinar: Aligning, Automating, Winning

Join Dan Russo, Senior Manager of Operations Intelligence, for an in-depth discussion on how Dealertrack, leading provider of integrated digital solutions for the automotive industry, transformed their DevOps processes to increase collaboration and move with greater velocity.

Question has a verified solution.

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

Suggested Solutions

For those of you who don't follow the news, or just happen to live under rocks, Microsoft Research released a beta SDK (http://www.microsoft.com/en-us/download/details.aspx?id=27876) for the Xbox 360 Kinect. If you don't know what a Kinect is (http:…
Real-time is more about the business, not the technology. In day-to-day life, to make real-time decisions like buying or investing, business needs the latest information(e.g. Gold Rate/Stock Rate). Unlike traditional days, you need not wait for a fe…
Two types of users will appreciate AOMEI Backupper Pro: 1 - Those with PCIe drives (and haven't found cloning software that works on them). 2 - Those who want a fast clone of their boot drive (no re-boots needed) and it can clone your drive wh…
Nobody understands Phishing better than an anti-spam company. That’s why we are providing Phishing Awareness Training to our customers. According to a report by Verizon, only 3% of targeted users report malicious emails to management. With compan…

821 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