Calling Function On DLL To Get Data From Structure?
Apr 16, 2012
I have problem about how I call a function on DLL to get data from a structure. Have a C++ example about how it's works the library, and I want to use it on vb.net. his is the working c++ example:
Declaration:
BOOL (WINAPIV* MyFun)(DWORD start1, DWORD stop1, P_RESULT pResult, PDWORD pTpNum, myCALLBACK lpFunc) = NULL;
Call:
// pStruc = RESULT structure
// TrpNum1, TrpNum is ULONG
ULONG TrpNum1=0;
MyFun(Start,Stop,pStruc+TrpNum,&TrpNum1,&myCB);
Callback:
void __stdcall myCB (RESULT *pStruc) {
printf ("%.3f", (double)pStruc->val1);
tpn++;
[Code] .....
The error is this: "Attempted to read or write protected memory. This often indicates that other memory is corrupt."
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May 11, 2011
I created a DLL with vb.net, this DLL uses a Structures for passing values to/from the functions.
Now I'm trying to use this DLL in my application, but when trying to call a function of the DLL with a structure(of my application, which is the same as in ther DLL) it tells me something like: "Unable to convert application.structure to DLL.structure".?
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Jul 7, 2009
I'm running around a problem I can't figure out. In my application I have to usethen MAPIInitialize function to initialize the MAPI32 and doing some work ...
<DllImport("MAPI32.DLL", CharSet:=CharSet.Ansi)> _
Private Function MAPIInitialize(ByVal lpMapiInit As IntPtr) As Integer
End Function
[code]....
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Feb 17, 2011
I'm currently working with a client's VB.Net code, which was developed for them by a small development shop a few years ago and which they purchased and have been maintaining and uprgrading since. This client's primary developer is out on indefinite (likely permanent) medical leave and I'm now filling in until they bring in a full timer (as I'm a contractor here). My current task is to add some functionality to a the VB.Net code they purchased. I'm finding practices and techniques in the code that absolutely baffle me and can't make the code do what I want. I'm starting to wonder if it's me and was hoping to get some thoughts on the code I've encountered.
For example: Setting a variable to accept the result of a function by calling the function with many parameters, clearing the parameters in the function, setting them to some value, calling another function with those new values, then never using the values returned by the functions. I'll add a code snippet in the first comment since this is already getting long.
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Sep 14, 2010
I have a function where I am performing a lot number of database operations inside a Sub. The operation when called directly like:ExecProcess()
takes about 11 seconds to run.However, if I create a Delegate, and call the sub using BeginInvoke(), the very same process takes over 40 seconds to execute.Here's the threaded code:
Protected del As ProcessDelegate
Protected Delegate Sub ProcessDelegate()
del = New ProcessDelegate(AddressOf SELocal.ExecJob)
Dim cb As New AsyncCallback(AddressOf Me.ExecJobComplete)
del.BeginInvoke(cb, del)
Anyone know what may cause a function to take longer inside a new thread, rather than calling directly?
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Mar 30, 2012
I am having a problem with the BackOrdered Function of my program. I can`t get it to say anything but 0 when I run the program. Another problem I am having is the input box pops up like 6 times and it`s only suppose to once. [Code]
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Apr 1, 2009
I am attempting to create a generic function that the students in my introductory VB .NET course can use to search a single dimension array of a structure.[code]...
My question is: Is there a way to reference the individual structure fields in the array from inside the function? I was trying to make it generic so that the student could simply pass their array into the function - their structure may be named differently than mine and the field names may be different.
I suspect there are other ways to deal with this situation, but I was trying to keep it to just a simple single-dimension array of a structure. I don't think it is possible to do what I want, but I wondered what others thought.
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Apr 24, 2012
I've this code, but there is a problem with setting values. I get "null object" error. how to work properly with functions.
Public Structure Results
Dim Nickname As String
Dim Result As Integer
[Code].....
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Dec 22, 2009
I want my function to return a value of a structure. The function is supposed to change the values and then return the answers in one structured value. Here is my code... as you can see it does not work... it needs a LOT of things. I placed question marks were i am really lost.
[Code]...
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May 11, 2010
I have a question: How can I make a function or sub run inside a structure when a variable in this structure changes? As example I have this function:
Public Structure Texture
Sub New(ByVal TexturePath As String)
Me.Path = TexturePath
Me.Image = LoadImage(TexturePath)
End Sub
Public Path As String
Public Image As Image
End Structure
And somewhere this happens:
Dim t As New Texture("path ooldfilename.tga")
t.Path = "path o
ewfilename.tga"
I want it to automatically load the image when the "Path" variable changes. Is the only solution making an extra sub and run that? It would really decrease my code size if it changes on variable change.
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Nov 21, 2010
Say I do this
Public Function CheckWebCamVF() As BusinessProfilesBO.VFCheck
checkwebcamVF.isactive = true
return checkwebcamVF
[code].....
I seem to be getting null referance errors using the first one.I am trying to get my code as fast and as correct as possible
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Oct 3, 2011
I have used the PInvoke Signature Toolkit to create VB.NET function definitions for three fairly simple C functions contained in an external DLL. The problem is that two of the parameters are structures so pointers need to be sent and one structure (fileview) is undefined.
OpenFileView(filename, &fileview_ptr)
ReadFileInfo(fileview_ptr, &fileinfo_ptr)
The structure of fileinfo is defined so I can create a structure definition in VB.NET and create an IntPtr to that structure with Marshall.AllocHGlobal. And then I can use Marshall.StructureToPtr to copy the data and do the inverse when the data is returned.
[Code]...
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Dec 7, 2009
I'm having some problems calling a C function from a DLL. The function is returning -101 which translates as a "bad parameter". The values I am passing have been returned from another, successful function call, so my current assumption is that I've built the structure incorrectly.The function definition is:
int sm_switch_channel_input(struct sm_switch_channel_parms *switchp)
Parameters
*switchp (a structure of the following type):
typedef struct sm_switch_channel_parms {
[code].....
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Mar 18, 2009
in a DLL that takes a pointer to a structure as a parameter.The C and VB code is as follows.Am I passing the structure in calling the DLL correctly? I am asking because the API call returns a valid error code indicating error opening the com port specified. I tried all valid ports (com1 on a Vista 32 machine with a USB-Serial device and com1 defined in device mgr, com1 and com2 on a desktop with winxp and 2 real serial ports).I dont have the code for the DLL and cannot debug into the DLL code.
C code
typedef struct _SETUPPR {
CHAR Port[5];
[code].....
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Mar 15, 2011
I'm sure this is a pretty simple question but I can't seem to find the answer on Google. Say I've got a function that does some stuff and returns a string. I can assign its return value to a variable:
Dim result As String = MyFunction()
But sometimes I want to perform the actions within the function but I don't care about the return value. I know I can simply call the function from code.
Sub Main()
' Code
MyFunction()
' More Code
End Sub
This works and does exactly what I need it to. My question is - are there any issues or pitfalls in doing this? Particularly I want to make sure I'm not introducing any performance or memory leak issues.
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Apr 9, 2010
The function is something like this: "function recieveFindPlayerResponse(displayString)"Now, how can I call it. I was trying this:Call AxShockwaveFlash1.CallFunction("_root.recieveFindPlayerResponse(displayString)")And before I had this, I had a Call function which defines displayString. (Works, as I've tested it before, and no error is given to this.)Now, how can I call a function like the above?
And example of what the code looks like from ******* swf decompiler is:
function recieveFindPlayerResponse(displayString)
{
[code].....
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Mar 17, 2010
in VVB.net I have a string that contains the name of a function, say dim funcstr as string = "MyFunc1". How do I call the function or sub whose name is contained in the string funcstr (in this case, MyFunc1)?
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Feb 28, 2012
going to need to call unction within a FoxPro program. I believe within my VB program I will need to create a service which will need to cal
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Nov 7, 2011
I'm a beginner when it comes to Visual Basic coding and I need some help with an error I'm getting. I'm trying to pass a structure array to a function to figure out a student's grade. I'm getting the error that 'QuizOne' is not a member of System.Array. Here is my code:
[Code]...
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Feb 2, 2012
I have a structure to hold a student name, an array to hold 5 test scores, and an average score. I have created an a array of structures for 6 students. User input is setup through text boxes. I want to calculate the average for each student. I have made a function to do this. What I am having trouble with is how to pass the array of test scores to the function.
Here is what I have so far:
CODE********
Public Const intMAX_STUDENTS As Integer = 6
Public Const intMAX_NUMTESTS As Integer = 5
Public student(intMAX_STUDENTS - 1) As StudentData
[Code].....
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Nov 25, 2010
I am trying to do a simple program where I have a public structure and public function in a code file, the problem is I want to return two integers. Here is the code from my code file.
[Code]...
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Sep 24, 2010
I have a windows app that references a web service I created. In the web service, I created a function that needed to return more than one value. Because of this, I created a public structure in the web service:
Public Structure MyRecordSet
Public lstOfDataInRecord As List(Of String)
Public iNumberOfRecords As Integer
End Structure
Here's the function - the return value is MyNewRecordSet:
Dim MyNewRecordSet As MyRecordSet <WebMethod()> _
Public Function GetDataReturnList(ByVal sql As String, ByVal sTableName As String) As MyRecordSet
MyNewRecordSet.lstOfDataInRecord = New List(Of String)
[Code] .....
Anyway, I see it's a conversion issue, but not sure how to resolve it. This is my first attempt to use a public structure in a web service and receive a return on it from my app.
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May 8, 2012
I have an aspx page populated with data from an access database using this code:
<asp:datalist id="bookData" runat="server" RepeatDirection="Horizontal" RepeatColumns="3">
<ItemTemplate>
[Code]....
I would like each entry of data to have a button associated with it that could call a server function to submit data to a database. I currently have the button implemented, but no idea how to go about calling a function that would be able to detect what button was clicked.
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Jun 14, 2012
i have this question i was trying to find a way to call a javascript function from asp controllers and i did here is the code :
<script type="text/javascript">
function hello() {
alert("hello world")
[Code]....
and i want to call it from a javascript function so it will be like controller----call---> javascript ---call--->code behind
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Sep 27, 2011
I've designed a Windows Service in Visual Basic 2005 that needs to call some functions from a DLL written in Delphi 5. If I try to add this DLL as a reference, I get this error:
"A reference to 'C:ProjectsServiceProMDPUpdateServiceMessageStubApplicationSPHost.dll' could not be added. Please make sure that the file is accessible, and that it is a valid assembly or COM component."
I assume that it is just not possible to add this DLL as a reference to my VB2005 project, since the DLL was written in an old version of Delphi, correct? This isn't a big deal, as I can just use the DllImport function from System.Runtime.InteropServices, but if it is possible, adding it as a reference would be preferred.
My other question is, how would you be able to call a function from the DLL using DllImport, if the function you are trying to call takes a Delphi record data type as a parameter (if this is possible)? If possible, would I need to pass each field in the record separately or would I be able to define a structure in my VB app that mirrors the record definition in the Delphi DLL and pass that? Or, would it be best if I just created another function in the Delphi DLL that took various string/integer/boolean/etc. parameters that I could call from VB that would then call the original function in Delphi? I tried searching the internet for this specific question, but I couldn't find anything that looked useful.
[Code]...
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Jun 2, 2010
I have an XML file with a list of tasks to be executed. One of the elements of the XML file is funcName (function name), which is the name of a function to be executed in my Visual Basic.NET application (v4).I can retrieve the string name of the function, but how do I go about running it? I have two Class files, GUI and DISP.[code]
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Sep 2, 2011
Is it advisable to call a function from another form?Does it have any side effects on the system while running, like more process will consume?I have a function that will set the background in a form, it will make the image stretch, backcolor transparent and will set the picture. If I will use that function in other 15 FORMS I can minimize my code.
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Sep 24, 2010
I have an 100 aspx files with one module file for code. All these aspx files have the same backend function, so i created on public module for all these files to access. These files are in the same folder. But for some reason the aspx files cannot access the function from that module.
mod1.vb Code (.vb file)
Public Module Allinone
Sub Allinone_Load(ByRef Page As Web.UI.Page)
[Code]....
I am at a roadblock of why the aspx files wont read this module? Also all these files are in the same directory
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Nov 6, 2009
I have a couple of threads running. One is a trigger which picks up a system event, the other processes stuff. When the trigger picks up the event I want it to notify the processor thread to do stuff. The threads are both started within the same class and can access the thread-object of the other thread. How do I set up the function call though?
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Jun 2, 2010
Question: I want to call a generic function, defined as:
Public Shared Function DeserializeFromXML(Of T)(Optional ByRef strFileNameAndPath As String = Nothing) As T
Now when I call it, I wanted to do it with any of the variants below:
Dim x As New XMLserialization.cConfiguration
x = XMLserialization.XMLserializeLDAPconfig.DeserializeFromXML(Of x)()
x = XMLserialization.XMLserializeLDAPconfig.DeserializeFromXML(GetType(x))()
x = XMLserialization.XMLserializeLDAPconfig.DeserializeFromXML(Of GetType(x))()
But it doesn't work.I find it very annoying and unreadable having to type
x = XMLserialization.XMLserializeLDAPconfig.DeserializeFromXML(Of XMLserialization.cConfiguration)()
Is there a way to call a generic function by getting the type from the instance ?
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