Question

Trying to use IndexOf with string / byte array that is larger than 32,767

Asked by: blandyuk

Hi all,

I have a problem where I'm loading around 2MB of data either as a string or a byte array and trying to do an "IndexOf" to find the position of certain characters, (not just 1).

Problem is that the .NET "IndexOf" function only works with 2 byte integers, meaning it can only handle up to a number of 32,767. Why did they not create this function to use a 4 byte long? I have written a function to get around this but I have found the same problem with all the other functions:

(for strings)
.SubString

(for byte arrays)
.Skip
.Take

Presume I'm going to have to adapt around this limitation but if someone can find an easy solution that would be great. Here is the re-written IndexOf I have done:

Public Shared Function IndexOfEx(ByRef input() As Byte, ByVal search As String, Optional ByVal start As Long = 0) As Long
        ' // Default position is -1
        Dim pos As Long = -1
        Dim bSearch() As Byte = Encoding.ASCII.GetBytes(search)
 
        For i As Long = start To input.LongLength - 1
            If input(i) = bSearch(0) Then
                ' // Set position marker
                pos = i
                For j = 1 To bSearch.Length - 1
                    If (i + j) = input.LongLength Then
                        ' // If past input data length, reset position marker
                        pos = -1
                        Exit For
                    ElseIf Not input(i + j) = bSearch(j) Then
                        ' // If bytes do not match, reset position marker
                        pos = -1
                        Exit For
                    End If
                Next
            End If
            ' // If match found, exit for and return result
            If pos >= 0 Then Exit For
        Next
 
        Return pos
    End Function

                                  
1:
2:
3:
4:
5:
6:
7:
8:
9:
10:
11:
12:
13:
14:
15:
16:
17:
18:
19:
20:
21:
22:
23:
24:
25:
26:
27:

Select allOpen in new window

This Question has been solved and asker verified All Experts Exchange premium technology solutions are available to subscription members.

Subscribe now for full access to Experts Exchange and get

Instant Access to this Solution

  • Plus...
  • 30 Day FREE access, no risk, no obligation
  • Collaborate with the world's top tech experts
  • Unlimited access to our exclusive solution database
  • Never be left without tech help again

Subscribe Now

Asked On
2009-10-28 at 06:56:36ID24850861
Tags

IndexOf

Topics

Miscellaneous Programming

,

Microsoft Visual Basic.Net

,

Programming for ASP.NET

Participating Experts
1
Points
500
Comments
8

Trusted by hundreds of thousands everyday for fast, accurate and reliable tech support.

  • "The time we save is the biggest benefit of Experts Exchange to Warner Bros. What could take multiple guys 2 hours or more each to find is accessed in around 15 minutes on Experts Exchange." Mike Kapnisakis, Warner Bros.
  • "Our team likes having a resource that is more secure than just using Google and most experts using this service really know their stuff. It's nice to look here first versus using Google." Dayna Sellner, Lockheed Martin
  • "Anytime that I've been stumped with a problem, 9 out of 10 times Experts Exchange has either the accepted solution or an open discussion of the potential solution to the problem." Kenny Red, eBay Inc.

See what Experts Exchange can do for you.

Got a question?

We've got the answer.

Experts Exchange has been collecting answers to technology questions since 1996…3 million and counting! If you have a question, chances are we already have your answer.

Screenshot of Experts Exchange Knowledgebase

Need individual assistance?

Our experts are ready to help.

If you can't find the exact answer you're looking for, ask our exclusive community of 50,000 experts. You’ll get a personalized answer from a trusted professional.

Screenshot of Experts Exchange Knowledgebase

Want to learn from the best?

Read articles from industry experts.

Thousands of free tech tips, tricks, how-to’s and tutorials are available in our peer reviewed articles section. See for yourself how smart our experts are, no login required.

Screenshot of an Article

Working on a long term project?

Store your work and research.

Save solutions to your questions, answers you’ve discovered through searching plus helpful articles in your personal knowledgebase for easy future access.

Screenshot of Experts Exchange Knowledgebase

Access the answers to your technology questions today.

Subscribe Now

30-day free trial. Register in 60 seconds.

What Makes Experts Exchange Unique?

Members of the expert community talk about why the experience at Experts Exchange is different than what you will find anywhere else.

Trusted by the world's most respected brands.

image of each brand's logo

Faithfully serving IT professionals since 1996.

Experts Exchange Logo

Try it out and discover for yourself.

Subscribe Now

30-day free trial. Register in 60 seconds.

Related Solutions

  1. IndexOf
    How do you use IndexOf to filter dash "-", comma "," and decimal point "." . MsgBox box would say wrong format.Thanks

Free Tech Articles

  1. WARNING: 5 Reasons why you should NEVER fix a computer for free.
    It is in our nature to love the puzzle. We are obsessed. The lot of us. We love puzzles. We love the challenge. We thrive on finding the answer. We hate disarray. It bothers us deep in our soul. W...
  2. SCCM OSD Basic troubleshooting
    SCCM 2007 OSD is a fantastic way to deploy operating systems, however, like most things SCCM issues can sometimes be difficult to resolve due to the sheer volume of logs to sift through and the dispe...
  3. Migrate Small Business Server 2003 to Exchange 2010 and Windows 2008 R2
    This guide is intended to provide step by step instructions on how to migrate from Small Business Server 2003 to Windows 2008 R2 with Exchange 2010. For this migration to work you will need the fo...
  4. Create a Win7 Gadget
    This article shows you how to create a simple "Gadget" -- a sort of mini-application supported by Windows 7 and Vista. Gadgets can be dropped anywhere on the desktop to provide instant information, ...
  5. Outlook continually prompting for username and password
    There have been a lot of questions recently regarding Outlook prompting for a username and password whilst using Exchange 2007. There are a few reasons why this would happen and I will try to cover t...
  6. Backup Exchange 2010 Information Store using Windows Backup
    There seems to be quite a lot of confusion around the ability to backup Exchange 2010 using the built in Windows Backup feature. This stems from the omission of this feature prior to Exchange 2007 s...

Cloud Class Webinars

  1. Avoiding Bugs in Microsoft Access
    Alison Balter takes and in-depth look at avoiding bugs in Access. In this webinar you will learn about using the immediate window to debug your applications, invoking the debugger, using breakpoints to troubleshoot, stepping through code, setting the next statement to execute, ...
  2. Top 10 Best New Features in Visio 2010
    Scott Helmers gives live demonstrations of the top 10 new features in Visio 2010. This webinar will teach you how to create compelling diagrams by adding shapes to the page with a single click, linking the shapes in a diagram to data in Excel (or SQL Server, or SharePoint), ...
  3. IT Consultant Business Secrets Revealed
    Michael Munger, Experts Exchange tech pro and IT consultant, pulls back the curtain on his very successful businesses and answers question on every IT consultant and business owner should know about. He shares secrets on what he did to solve the 5 most common problems in IT, ...
  4. Disaster Recovery and Business Continuity
    Quest CTO, Mike Billon, gives an overview of the steps involved in building a dunamic disaster recovery plan. Through case studies and an examination of software/hardware tooles for monitoring and testing, you'll gain a better understandin of where you are, where you want ...
  5. Organize Your Visio Diagrams with Containers and Lists
    Scott Helmers uses cross functional flowcharts, wireframe diagrams, data graphic legends and seating charts to teach you: how to ustilize all three new structured diagram components in Visio 2010, the best practices for organizeing shapes in previous version of Visio, how to organize ...
  6. How to Us Objects, Properties, Events and Methods in Microsoft Access
    Alison Dalter gives an in-depbth look at objects, properties, events and methods in Microsoft Access. In this webinar you will learn about using the object browser, referring to objects, working with properties and methods, working with object variables, understanding the ...

Join the Community

Give a Little. Get a Lot.

Join the community of experts here and help other tech pros by answering question in your area of expertise. You can earn FREE access to all Experts Exchange's premium features and resources.

Join the Community

Answers

 

by: bhmahlerPosted on 2009-10-28 at 07:40:50ID: 25683739

The return value of IndexOf is System.Int32 which is a 4 byte integer
http://msdn.microsoft.com/en-us/library/k8b1470s.aspx

 

by: bhmahlerPosted on 2009-10-28 at 07:41:57ID: 25683758

 

by: blandyukPosted on 2009-10-28 at 09:29:55ID: 25685077

That's an interesting bug in the MS knowledge base as also in that page, it references to code which specifically says it's a integer, also VB.NET confirms it's an 2 byte integer value, not an Int32:

Dim instance As String
Dim value As String
Dim returnValue As Integer       <------------ Integer

returnValue = instance.IndexOf(value)

I've also tried this already and it fails with any IndexOf searches over 32767.

 

by: blandyukPosted on 2009-10-28 at 09:38:58ID: 25685190

OK, I'm confused now as I've just got it working. Sorry, please ignore my last comment.

 

by: blandyukPosted on 2009-10-28 at 09:45:58ID: 25685276

This is interesting, isn't the Integer type in VB.NET a 2 byte number? Long is 4 byte. Just that I have assigned a number greater than 32767 into an integer variable and it's ok, even with option strict on. Think I'm having a stupid day today LOL.

 

by: bhmahlerPosted on 2009-10-28 at 09:54:02ID: 25685376

no, in .net integer is 4 byte type and long is 8 byte

 

by: blandyukPosted on 2009-10-28 at 09:57:41ID: 25685418

Thanks for that, just found that out now as well. I know where I've gone wrong, my old VB6 programming is creeping back up on me :( gotta get outta that!!!!

Thanks for sorting that :)

 

by: blandyukPosted on 2009-10-28 at 09:58:32ID: 31646960

Me being stupid and thinking of a VB6 16bit Integer.

Cheers.

20120131-EE-VQP-002

3 Ways to Join

30-Day Free Trial

The Experts

98% positive feedback on 31,087 answers since March 2000. angeliii is a Microsoft Most Valuable Professional for his work with MS SQL Server & Develoment.

He has also proven his knowledge of Visual Basic Programming, PHP Scripting and Oracle Databases.

The Experts

97% positive feedback on 10,752 answers since July 2000. lrmoore has more than 18 years experience in the networking industry.

The six-time Mircosoft MVPs specialties include firewalls, virtual private networking, and network management.

Testimonials

"...and excellent source for support... Kind of like having your very own IT dept." Electriciansnet

Testimonials

"I was apprehensive at signing up at first. However... it has already made my life as an IT administrator much easier." JaCrews

Testimonials

"WOW! You guys have great, active, and knowledgeable people on here." moore50

Business Clients

Business Clients

In the Press

"If you’ve got a question... Experts Exchange can supply an answer.”

In the Press

"...an invaluable aid for both IT professionals and those who require tech support."

In the Press

"where IT professionals provide quick answers on just about any topic"

Business Account Plans

Loading Advertisement...