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either that or, better, reset the variable you were using when you need to.
Now name two reasons why the latter is better!
 Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]
I only read code that is properly formatted, adding PRE tags is the easiest way to obtain that. All Toronto weekends should be extremely wet until we get it automated in regular forums, not just QA.
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Hi all,
I have a little problem with a pair of arrays, when them are involved in a comparation work:
In particular, I have an Array A As String and another array B As String.
Normally the program works with a single array A, but sometimes I need a second array B.
Array A is filled with numerical string (sometime with up 15000 elements).
Array B is filled with numerical string (sometime with up 15000 elements).
The code works in this way:
Each element of array B is compared with Each element of array A.
If a value of array B is = to some value in array A then the value in the array B is removed and the array is resized (progressively size-decreased) but preserving remaining different values (Redim Preserve).
In this way, at the end of comparation loop, the array B will contain only values that are not already contained in array A.
The code seems to be perfectly working until the number of elements in array A and B is down about 2200 + 2200 elements, but if numbers of arrays element go up, the program seems to work (in an infinite loop) but in reality it is quited (closed) from O.S.
In the fact the program name disappears from list of running program.
The following is the schematic code:
Do Until IndexB = ArrayB.GetLength(0)
For IndexA = 1 to ArrayA.GetLength(0)
If Val(ArrayB(IndexB)) = Val(ArrayA(IndexA)) Then
ArrayB(IndexB) = ArrayB(ArrayB.GetLength(0) - 1)
ReDim Preserve ArrayB((ArrayB.GetLength(0) - 1) - 1)
IndexB = IndexB - 1
Exit For
End If
Next
IndexB = IndexB + 1
Loop
Application is running in a Windows Mobile 6.1 Device.
Apparentely seems to be a memory problem, but I don't think so, because size of arrays is not exagerate and the device have enough available memory.
Thanks for help.
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Hi,
this is horribly inefficient for many reasons:
- you are converting strings to numbers all the time; it they really are numbers, store them in a numeric data type, not string.
- ReDim Preserve is expensive as it has to allocate a new array, then copy all the data. When the number of items in a collection varies, you should consider using a real collection instead of an array; use a collection type if those are available, or create your own linked list structures.
- For two arrays of size S1 and S2, you are performing S1*S2 comparisons. It would be cheaper to sort the first array, sort the second array, and then perform the equivalent of a merge-sort on both. This will improve speed dramatically and reduce the memory load drastically.
So throw it all out; start using lists of numbers; then sort and merge. It would handle millions of numbers in a matter of seconds.
 Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]
I only read code that is properly formatted, adding PRE tags is the easiest way to obtain that. All Toronto weekends should be extremely wet until we get it automated in regular forums, not just QA.
modified on Friday, February 26, 2010 1:50 PM
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As an alternative to the sort and merge approach, you may also try using a Dictionary/HashSet. If you have .NET 3.5 available, you could use the Except extension method (which I understand uses a HashSet internally) like so:
Dim temp = ArrayB.Select(AddressOf Double.Parse) _
.Except(ArrayA.Select(AddressOf Double.Parse)) _
.ToArray()
If you don't have the LINQ methods, you could do this yourself:
Dim parsedToRemove As New Dictionary(Of Double, Double)
Dim noDuplicates As New List(Of Double)
For Each parsedA In Array.ConvertAll(ArrayA, AddressOf Double.Parse)
If Not parsedToRemove.ContainsKey(parsedA) Then
parsedToRemove.Add(parsedA, parsedA)
End If
Next
For Each parsedB In Array.ConvertAll(ArrayB, AddressOf Double.Parse)
If Not parsedToRemove.ContainsKey(parsedB) Then
noDuplicates.Add(parsedB)
End If
Next
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Thanks for replies.
Both contains good ideas to resolving the problem.
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Hello
How can i make my program exit say when you would press somting like Ctrl+Esc ??
Thanks
Bob
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What kind of application is it?
If it's a WinForms app, then simply Close() the main form when the right key combination is found in one of the KeyPress/KeyDown events.CQ de W5ALT
Walt Fair, Jr., P. E.
Comport Computing
Specializing in Technical Engineering Software
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Right on Man
I got it thanks
Bob
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Dear Friends.
I need to set a shortcut key for "activate my program" or "my program show a message" or ... . that means when user is everywhere of windows or on any program, he press Alt+F8 and then my program activates.
How can I set a shortcut key that works on everywhere of windows?Mehdi Ghiasi
modified on Thursday, February 25, 2010 5:42 AM
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See this[^] useful article about global keyboard and mouse hooks.
I hope this helps.
Regards
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Thanks a lot  Mehdi Ghiasi
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You are welcome!
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I need to set the camera source for each of 4 video windows in C# without using the windows dialog box.
I have a video capture card that has 4 inputs that can be accessed simultaneously. I have a working application that calls the VideoCapture class. Each time after the first instance I get the Windows Video Device Selection pop up from which I have to manually choose the input for each remaining window. I could live with this except, whatever I choose as the last input is automatically assigned as the device to the first window the next time the application starts. This is unacceptable because the camera assignments are never in the same location.
I would prefer to assign each of the inputs in code and never see the Windows Video Device Selection pop up.
Anyone have an idea how to obtain and pass the device id to the WebCam_Capture.dll?
Thanks
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I also have the same problem...
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My company has a database (MSSQL 2005) system for managing and archiving communications that contain certain sensitive information. It is web-based and allows us to transmit information via https rather than potentially unsecured email. It uses two tables, one for the message itself and one for any attachements that go along with the message. The attachement table is very simple, with only three columns: INT CommId (which maps to the primary key of the messages table), VARCHAR(100) Descr (a user-friendly name for the attached file) and VARBINARY(max) Att (the attached file itself.) This system, clunky as it may seem, serves our security and data-retention needs very well and has allowed us to integrate it gracefully with several back-office apps.
We have an app written in VB6 that I am trying to translate to VB.net 2008. It processes client information and sends a secure communication to our field reps when something comes up for their attention. The communication has a PDF attachement which is the same for every rep but may be changed in the future.
The VB6 app uses the ADODB library -- specifically the ADODB.Stream object -- to put the PDF into the Attachement column. The code looks like this:
Set Strm = New ADODB.Stream
Strm.Type = adTypeBinary
Strm.Open
Strm.LoadFromFile DocPath
With AdodbCmd
.CommandText = InsertQuery
.Parameters.Append .CreateParameter("@CommId", adInteger, adParamInput, , CommId)
.Parameters.Append .CreateParameter("@Descr", adVarChar, adParamInput, 100, Descr)
.Parameters.Append .CreateParameter("@Att", adLongVarBinary, adParamInput, 2147483647, Strm.Read)
.Execute
End With
I want to do exactly this same thing using the 3.5 framework, without having to interop with the ADODB COM library. I cannot guarantee that future versions of the PDF will be below the 8000 character limit, so any solution needs to handle a file of arbitrary length.
Suggestions?modified on Thursday, February 25, 2010 9:59 AM
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The ADO.NET replacement you are looking for is based around the SqlCommand, SqlConnection classes."WPF has many lovers. It's a veritable porn star!" - Josh Smith As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.
My blog | My articles | MoXAML PowerToys | Onyx
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I am very familiar with SqlConnection and SqlCommand; I have been using them extensively for some time. My question was about getting a large binary file from the file system into a VARBINARY(max) database column. I can do this pretty easily using ADODB.Stream, as shown in my code in the OP. I'd like to learn the .Net equivalent and avoid using COM interop.
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You should set the parameter to SqlDbType.VarBinary. Set SqlParameter.Value to the byte[] that corresponds to the byte array you have read in from the file (it is just a stream after all)."WPF has many lovers. It's a veritable porn star!" - Josh Smith As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.
My blog | My articles | MoXAML PowerToys | Onyx
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Your solution is actually one of the first things I tried, but I kept getting an exception when the code was executed. Turns out, the problem -- revealed by an inner exception and not by the outer one I was reading -- was bad syntax.
Yeah, it's working now, and without running into a 8000 byte limit that some documentation seemed to state: the PDF file is 97k. I assume that the only practical limit to this method is available memory? And I assume there is no problem with streamlining the parameter declaration to AttParam.Value = System.IO.File.ReadAllBytes(DocPath)?
Thanks for your assistance. Now, if you'll excuse me, I have a wall to bang with my head.
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TechBearSeattle wrote: I assume that the only practical limit to this method is available memory? And I assume there is no problem with streamlining the parameter declaration to AttParam.Value = System.IO.File.ReadAllBytes(DocPath)?
Shouldn't be any problems there, and I'm glad I could help."WPF has many lovers. It's a veritable porn star!" - Josh Smith As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.
My blog | My articles | MoXAML PowerToys | Onyx
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Dear friends on the block, my name is danso and i'm getting hands on .NET FRAMEWORK for the fist time.
I will be glad to get supports from anyone here. Thanks
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Thnaks....i now understand it's a programming language, with pre-biult codes that enhance on developing a system or application.
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danso sackey wrote: ....i now understand it's a programming language
Uhhh, read it again. No, it's not a programming lanugage.
The .NET Framework is a huge collections of classes that can be used acrossed a wide range of languages, all targeting the .NET CLR, making writing applications easier, among other things.
The .NET CLR is a managed execution environment that runs these applications.
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No it's not. It's a framework that provides common facilities for any language that subscribes to it to develop against. These languages must support the common runtime and common language specs to be classed as .NET compatible."WPF has many lovers. It's a veritable porn star!" - Josh Smith As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.
My blog | My articles | MoXAML PowerToys | Onyx
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