Re: Need help converting CRC32 function in C to VB - Visual Basic Discussion Boards

Yeah, that works. But, when your forms get more complicated, you'll find that using Update can cause you some unwanted side-effects. Just keep a heads up...

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Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007, 2008

hi..

what would be an alternative to update()

if u can. plz. post some code.

PS : and do u mean i look like a beginner because i'm not using oop ???

hugblue wrote:
if u can. plz. post some code.

There are thousands of examples all over the web. All it takes is a little Google, like search for "vb.net BackgroundWorker" or "vb.net thread tutorial".

hugblue wrote:
PS : and do u mean i look like a beginner because i'm not using oop ???

Yes, among a list of other things about your code...

A guide to posting questions on CodeProject[^]

Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007, 2008

thz dave..

will look into it. and start study some oop.
but the logic in it is damn hard and there are so many new things to learn. Ss.

but thz. for the answers.

hi all
i m in window application
i have created a project in VS2008 in VB.Net
Now i want to create a setup for my client but i dont know how to create a setup for window project
Please help
its urgent

Thanks
Jagwinder Walia

Er. Jagwinder Singh

You have an option in Visual studio itself - [^]

Below is a C function for calculating a custom CRC32 using a static table. I need to create the same function in VB, but I know very little C language. I need to be able to calculate the CRC32 for a file selected by the user.

/*
// *****************************************************************************
CRC32
// *****************************************************************************
*/

/*------------------------------------------------------
lookup toble for CRC32 generation
------------------------------------------------------*/
#include <platform.h>
#include "cache.h"

unsigned long CRCtable[256] =
{
0x00000000L, 0x04c11db7L, 0x09823b6eL, 0x0d4326d9L,
0x130476dcL, 0x17c56b6bL, 0x1a864db2L, 0x1e475005L,
0x2608edb8L, 0x22c9f00fL, 0x2f8ad6d6L, 0x2b4bcb61L,
0x350c9b64L, 0x31cd86d3L, 0x3c8ea00aL, 0x384fbdbdL,
0x4c11db70L, 0x48d0c6c7L, 0x4593e01eL, 0x4152fda9L,
0x5f15adacL, 0x5bd4b01bL, 0x569796c2L, 0x52568b75L,
0x6a1936c8L, 0x6ed82b7fL, 0x639b0da6L, 0x675a1011L,
0x791d4014L, 0x7ddc5da3L, 0x709f7b7aL, 0x745e66cdL,
0x9823b6e0L, 0x9ce2ab57L, 0x91a18d8eL, 0x95609039L,
0x8b27c03cL, 0x8fe6dd8bL, 0x82a5fb52L, 0x8664e6e5L,
0xbe2b5b58L, 0xbaea46efL, 0xb7a96036L, 0xb3687d81L,
0xad2f2d84L, 0xa9ee3033L, 0xa4ad16eaL, 0xa06c0b5dL,
0xd4326d90L, 0xd0f37027L, 0xddb056feL, 0xd9714b49L,
0xc7361b4cL, 0xc3f706fbL, 0xceb42022L, 0xca753d95L,
0xf23a8028L, 0xf6fb9d9fL, 0xfbb8bb46L, 0xff79a6f1L,
0xe13ef6f4L, 0xe5ffeb43L, 0xe8bccd9aL, 0xec7dd02dL,
0x34867077L, 0x30476dc0L, 0x3d044b19L, 0x39c556aeL,
0x278206abL, 0x23431b1cL, 0x2e003dc5L, 0x2ac12072L,
0x128e9dcfL, 0x164f8078L, 0x1b0ca6a1L, 0x1fcdbb16L,
0x018aeb13L, 0x054bf6a4L, 0x0808d07dL, 0x0cc9cdcaL,
0x7897ab07L, 0x7c56b6b0L, 0x71159069L, 0x75d48ddeL,
0x6b93dddbL, 0x6f52c06cL, 0x6211e6b5L, 0x66d0fb02L,
0x5e9f46bfL, 0x5a5e5b08L, 0x571d7dd1L, 0x53dc6066L,
0x4d9b3063L, 0x495a2dd4L, 0x44190b0dL, 0x40d816baL,
0xaca5c697L, 0xa864db20L, 0xa527fdf9L, 0xa1e6e04eL,
0xbfa1b04bL, 0xbb60adfcL, 0xb6238b25L, 0xb2e29692L,
0x8aad2b2fL, 0x8e6c3698L, 0x832f1041L, 0x87ee0df6L,
0x99a95df3L, 0x9d684044L, 0x902b669dL, 0x94ea7b2aL,
0xe0b41de7L, 0xe4750050L, 0xe9362689L, 0xedf73b3eL,
0xf3b06b3bL, 0xf771768cL, 0xfa325055L, 0xfef34de2L,
0xc6bcf05fL, 0xc27dede8L, 0xcf3ecb31L, 0xcbffd686L,
0xd5b88683L, 0xd1799b34L, 0xdc3abdedL, 0xd8fba05aL,
0x690ce0eeL, 0x6dcdfd59L, 0x608edb80L, 0x644fc637L,
0x7a089632L, 0x7ec98b85L, 0x738aad5cL, 0x774bb0ebL,
0x4f040d56L, 0x4bc510e1L, 0x46863638L, 0x42472b8fL,
0x5c007b8aL, 0x58c1663dL, 0x558240e4L, 0x51435d53L,
0x251d3b9eL, 0x21dc2629L, 0x2c9f00f0L, 0x285e1d47L,
0x36194d42L, 0x32d850f5L, 0x3f9b762cL, 0x3b5a6b9bL,
0x0315d626L, 0x07d4cb91L, 0x0a97ed48L, 0x0e56f0ffL,
0x1011a0faL, 0x14d0bd4dL, 0x19939b94L, 0x1d528623L,
0xf12f560eL, 0xf5ee4bb9L, 0xf8ad6d60L, 0xfc6c70d7L,
0xe22b20d2L, 0xe6ea3d65L, 0xeba91bbcL, 0xef68060bL,
0xd727bbb6L, 0xd3e6a601L, 0xdea580d8L, 0xda649d6fL,
0xc423cd6aL, 0xc0e2d0ddL, 0xcda1f604L, 0xc960ebb3L,
0xbd3e8d7eL, 0xb9ff90c9L, 0xb4bcb610L, 0xb07daba7L,
0xae3afba2L, 0xaafbe615L, 0xa7b8c0ccL, 0xa379dd7bL,
0x9b3660c6L, 0x9ff77d71L, 0x92b45ba8L, 0x9675461fL,
0x8832161aL, 0x8cf30badL, 0x81b02d74L, 0x857130c3L,
0x5d8a9099L, 0x594b8d2eL, 0x5408abf7L, 0x50c9b640L,
0x4e8ee645L, 0x4a4ffbf2L, 0x470cdd2bL, 0x43cdc09cL,
0x7b827d21L, 0x7f436096L, 0x7200464fL, 0x76c15bf8L,
0x68860bfdL, 0x6c47164aL, 0x61043093L, 0x65c52d24L,
0x119b4be9L, 0x155a565eL, 0x18197087L, 0x1cd86d30L,
0x029f3d35L, 0x065e2082L, 0x0b1d065bL, 0x0fdc1becL,
0x3793a651L, 0x3352bbe6L, 0x3e119d3fL, 0x3ad08088L,
0x2497d08dL, 0x2056cd3aL, 0x2d15ebe3L, 0x29d4f654L,
0xc5a92679L, 0xc1683bceL, 0xcc2b1d17L, 0xc8ea00a0L,
0xd6ad50a5L, 0xd26c4d12L, 0xdf2f6bcbL, 0xdbee767cL,
0xe3a1cbc1L, 0xe760d676L, 0xea23f0afL, 0xeee2ed18L,
0xf0a5bd1dL, 0xf464a0aaL, 0xf9278673L, 0xfde69bc4L,
0x89b8fd09L, 0x8d79e0beL, 0x803ac667L, 0x84fbdbd0L,
0x9abc8bd5L, 0x9e7d9662L, 0x933eb0bbL, 0x97ffad0cL,
0xafb010b1L, 0xab710d06L, 0xa6322bdfL, 0xa2f33668L,
0xbcb4666dL, 0xb8757bdaL, 0xb5365d03L, 0xb1f740b4L
};

/*----------------------------------------------------------------------------
----------------------------------------------------------------------------*/
unsigned long CalcCRC(unsigned long val, unsigned char *buf, unsigned long len)
{
unsigned long accum;
EnableCaches();
for(accum = val; len > 0; len--, buf++)
accum = (accum<<8) ^ (CRCtable[(unsigned char)(accum>>24)^(*buf)]);
DisableCaches();
return accum;
}

Here is my proposed VB input to the function.

' CRC32:
Dim f As FileStream = New FileStream(txtFileName, FileMode.Open, FileAccess.Read, FileShare.Read, 8192)
crc = c.GetCrc32(f)
f.Close()

Any help or direction would be greatly appreciated!

The array can be declared in VB as

Dim CRCtable(255) As ULong = {  _
  ... Fill in with values. NB will need line continuation chars at end of each line
}

You can just copy and paste the existing declaration with three points to note.
First C does not have line continuation character so you'll have to add them.
Secondly, you don't need the ; after closing }.
Thirdly, the size needs to be changed from 256 to 255.

The function is trickier but this seems a reasonable attempt

Public Function CalcCRC(ByVal val, As ULong, ByVal buf as Byte[], ByVal len As ULong) As ULong
{
   Dim accum As ULong
   Dim i As Integer = 0
   ' Dont know what this does not standard C - EnableCaches()
   accum = val
   do while (len > 0)
      accum = (accum<<8) Xor (CRCtable((accum>>24) Xor buf(i)))
      len = len - 1
      i = i + 1
   loop
   ' Dont know what this does not standard C - DisableCaches()
   return accum
}

Possible problems:
1 The unsigned long type in C can be 4 or 8 bytes. The spec just says its size got to be at least as big as an int. So you might have to use UInt instead of ULong. The values in the array only take 4 bytes so my guess is you should use UInt.
2. A C unsigned char is essentially the same as a VB byte. So the unsigned char *buf parameter is pointing at an array of bytes (I assume of length given by len).
3. You might get off by one errors. C arrays always start at 0 with maximum index given by 1 less than in declaration. E.g int myArray[5]; gives an array of 5 elements with index 0 to 4.
4. I have no idea what EnableCaches/DisableCaches do - they are not standard C functions. My guess is they provide some sort of protection against array out of bounds exceptions.
5. This (accum>>24) Xor buf(i)) calculates an index into the array. You might have to do this using another variable. I'm not sure if this will always be in range 0 to 255. And you might have to do some casting to make it an integer.

Regards
David R

Hi,

I have two forms. The second form is called by the 1st one. I set color values for some global variables in 2nd form. The controls in 1st form uses this values for their background color.

The question is: Is there a way to set the 1st form's controls background color immediately when the variable recieves a value. I decided to use form1.refresh to see if the changes would take effect after assignment. But it didn't change. Is there a short way to realize that?

Thanks.

What a curious mind needs to discover knowledge is noting else than a pin-hole.

You have to write code on Form1 to set the BackColor of every control you want to change yourself. There is no magic that does it for you. The control have no idea that the value you used changed. They look at their own internal property values, not your "global" variable.

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Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007, 2008

I have a tcp server that accept connections and handle clients request. It has been running without any known issues for a few weeks. Recently I have made some mods to handle different requests and now I have been getting an InvalidOperationException Error "the Undo operation encountered a context that is different from what was applied in the corresponseding Set operation. the possible cause is that a contect was Set on the thread and not reverted(undone)" When i started getting this error, I reverted back to a previous version and now I am getting the error on that version. This makes me believe I have an underlying intermittent threading problem.

One of the things I am doing is creating a new instance of a custom class (Query) in which an instance of another custom class (Trigger) is passed by reference. From within query I am accessing properties and and manipulating data. Could this be causing the problem. Like i said before, It was working like this previously, this is a new error. I am having a hard time tracking down the error bc frankly i do not really understand it.

Hi,I was wondering if anyone can help me to generate a thumbnail images from a list of graphic files on a CD so I can catalog to content of each CD.
file types are *.jpg, *.Gif etc...

I am using VB 2008,

Thanks
Simon
sybaco@gmail.com Smile | :)

simon

There are a ton of thumbnail generation articles all over the web, including here at CP. All you have to do is Google for "vb.net create thumbnail image[^]" to find them. I'd tell you how to do it myself, but I wouldn't be adding anything to the couple hundred thousand explainations out there right now...

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Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007, 2008

Dave, Thanks, I just do not have the time I am a newbie so it will take me lots of time, so I have again visited Rentacoder, all is well and thank you again, Just for my own knowledge I will browse the web,
Simon

simon

Good Luckk with that!

A guide to posting questions on CodeProject[^]

Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007, 2008

Hi. I'm busy with a app that needs to print xml rendered by xslt. Currently I am printing with internet explorer in the following manner
<pre>
Dim internetExplorer As New SHDocVw.InternetExplorerClass() Dim webBrowser As SHDocVw.IWebBrowser2 = CType(internetExplorer, SHDocVw.IWebBrowser2) 'Make the web browser visible webBrowser.Visible = False 'Display empty page so we have something to manipulate. Dim noValue As Object = System.Reflection.Missing.Value webBrowser.Navigate("file://" + fileName, noValue, noValue, noValue, noValue) While webBrowser.Busy Threading.Thread.Sleep(500) End While 'Get access to the webbrowser's document. internetExplorer.ExecWB(SHDocVw.OLECMDID.OLECMDID_PRINT, SHDocVw.OLECMDEXECOPT.OLECMDEXECOPT_DONTPROMPTUSER, noValue, noValue) 'CType(internetExplorer.Document, mshtml.IHTMLDocument2).close() Marshal.ReleaseComObject(internetExplorer) Marshal.ReleaseComObject(webBrowser)
</pre>

I need to find a different way to do this as the above code gives a com exception. Or I need a workaround for the above code. If anybody can help I would greatly appreaciate it.
Stephen

Stephen Lintott Bsc IT (RAU)

Don't repeat the same question again and again in the same day. You just posted this 7 hours ago and haven't waited long enough for a response. I just started playing around with your code, not 2 minutes ago and need time to look it the problem.

A guide to posting questions on CodeProject[^]

Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007, 2008

Sorry I just under presure to get an answer for this. Any luck so far because I am stuck

Stephen Lintott Bsc IT (RAU)

Yeah, and I'm under pressure to test 96 applications by the end of this week...

CodeProject is supported entirely by people who volunteer their time. We get around to answering questions as much as we can whenever we can, but on our own time. We don't get paid to do this.

A guide to posting questions on CodeProject[^]

Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007, 2008

Dear All,

I am looking for to convert code of C# to VB.net is any possibility or guideline then please guide me.

Thanks

Sajjad Ali

It's not that different.

You can find "Resetta Stone" examples all over MSDN's documentation for the .NET Framework. There are line-for-line translations in C++, VB.NET, C# for most of the examples.

There are also online translation utilities. Just Google for "Convert C# to VB.NET code".

A guide to posting questions on CodeProject[^]

Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007, 2008

http://www.carlosag.net/Tools/CodeTranslator/[^]

http://www.developerfusion.com/tools/convert/csharp-to-vb/[^]

http://www.kamalpatel.net/ConvertCSharp2VB.aspx[^]

A friend who knows C# and VB.Net recommend the second.

hth

Samir R. Ibrahim

Hello all,I'm new to using Crystal Reports and VB.NET Programming here. I have try to Google for how it works. Currently I'm able to show my Blank Reports by Clicking a Button2. I have to ask anyone can tell me how to display my data using the Crystal Report? The following are the code I'm currently working with:

'When the following button Click,the Report will showout.
 Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Dim objRpt As New FrmCrystalRpt
        objRpt.strRptName = New CachedCrystalReport1
        
        objRpt.Show()

    End Sub

'The below is my ReportViewer WinForm
Public Class FrmCrystalRpt
    Public strRptName As Object
    Public strRptFilter As String

    Private Sub FrmCrystalRpt_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        If strRptFilter <> "" Then
            crptVW.SelectionFormula = strRptFilter
        End If
        crptVW.ReportSource = strRptName
        crptVW.Show()

    End Sub
End Class

Currently my report showing nothing,I'm wondering how could I make this report show my selection of data from the MySQL5.0 database?
I'm using MySQL ODBC3.51 Driver to connect my Database=logistic_sysdb.
I wish the Crystal Report can show my selection of data below:

Dim SQL4 As String
        selectmonth = ComboBox2.SelectedItem

        SQL4 = "SELECT * FROM lorry_commission WHERE Lorry_No='" & ComboBox1.SelectedItem & "' AND MONTH(Date)='" & selectmonth & "';"
       
        Try
            ObjMyConn.Open()
            ObjAdapter = New MySqlDataAdapter(SQL, ObjMyConn)
            ObjAdapter.Fill(ds, "Salary44")
        Catch ex As Exception
            MsgBox("Error: " & ex.Source & ": " & ex.Message, MsgBoxStyle.OkOnly)
        Finally
            ObjMyConn.Close()
        End Try

I guess some parameter is needed to be passed into the Crystal Report as well. How to do that?
Anyone can give me a sample is better so I can learn easier to solve this.

Thanks for reading.
Drex

You would need to assign a DataSource to the report. Take a look at this article [^]

I'm still wondering how to use that Crystal Report? Anyone can let me know how to show a dataset table result using a Crystal Report after clicking a button? And how can I pass 3 string parameter to the Crystal report?

Thanks for reading.

Drex