Pointers - Accessing Variable Addresses In .NET?
Dec 23, 2009
I have to upgrade a legacy VB6 app to VB.NET; this app uses a function call from a .dll that takes a memory address as one of it's parameters. The VB6 app does this with the VarPtr() function, but this function does not exist in .NET. How do I retrieve the memory location of a variable in .NET?
[Code]...
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Jan 17, 2010
Since vb doesnt support pointers but c# does. I am using a wrapper dll that requires a pointer to some singles to be passed within the method. I get an error that the method has some parameter types that are not supported. How can i pass a pointer to this method if vb .net doesnt support pointers.
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Aug 3, 2010
I am trying to develop a small application that logs the IP address and or computer names of all the users [my domain or remote location] that accessed files or folders on the server.
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Mar 24, 2010
How do I access the sContents variable in loadBoard() sub to LoadTable() sub
Sub loadBoard()
Dim oFile As FileStream
Dim oReader As StreamReader = Nothing
Dim sContents As String
[code]....
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Mar 9, 2012
I have this,
Public Class posData
Public Property strLabel As String
Public Property strX As String
[Code]....
then i want to loop through all the objects within my list so i have a for each position in posList, inside this is where the problem occurs, i want to be able to write something like this, a1.blnavail, this is not happening however, i know i can use position.blnavail but i need to hardcode the position for my logic to work correctly
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Mar 4, 2009
I have two variables, X and Y (this is just figurative)
X = 123
Y = X
How can I get that X out of the Y to be able to get the contents of X from the Y? I just want to be able to do something like tell a textbox to display the contents of the variable within the Y variable (thus, the contents of X).
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Nov 19, 2009
The subject almost sums this up. I have dimensioned a variable 'y' inside a for loop. If i then try and access this outside of the for loop I cannot. What is the reason for this and how can I correct it? Unfortunately I am not able to Dim the variable 'y' outside of the for loop.
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Nov 12, 2010
i have
VariableA as Class1
Variable1 as string
Variable1 = "VariableA"
I want to be able to use Variable1 to get access to VariableA(?).
So i want to able to do something like
VariableA.Property1 = "test"
But like this:
Variable1.Property1 = "test"
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Jan 10, 2012
I currently have two forms, and I need to share the value of a variable in one of them.
I declared the variable to be 'Public Shared', and assigned a value to it. However,
when I inspect the value it appears as 'Nothing'. Here is the snippet:
Public Class A
Public Shared sVar As String = Nothing
Private Sub A_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
[Code]....
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May 23, 2012
I'm trying to iterate through a group of ComboBoxes and set a property using a concatenated string & variable to represent the name of the control. However, I can't get the instance of the form to recognize the (String & Integer_Variable) as one of its controls -- and so it doesn't recognize any of the appropriate properties or subroutines as members of the System.Windows.Forms.Control.Is there a cleaner way to do this?
For myTempCount = 1 To 6
If tempValue < Me.("ComboBox" & myTempCount).Items.Count Then
ComboBox.SelectedIndex = tempValue 'appears to work -- how?[code].....
This code was originally VBA / VB6, which I put through ArtinSoft's Visual Basic Upgrade Companion (VBUC). FWIW, I'm using Microsoft Visual Basic 2010 Express.
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Sep 30, 2010
Is there any way to access your variable names at runtime? Is there any kind of collection you can loop through?
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Dec 15, 2010
Id'like to pass some variables (string and integers) to a class, and when I call a method of that class, it has to change the original variable.I know it was not impossible in C#, but I'm using VB2010, I made a C# project into my solution, but methods using pointers are hidden into VB. How can I make that kind of change?
An example:
Sub ChangeValues()
Dim A As Integer = 1, Str As String = "Start String"
Dim X As MyClass(A, Str)
X.ChangeInt(2)
[code]....
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Jun 9, 2010
have a 2d array of structures that holds about 5 or 6 details on each cell. The array size will not be known at compile time so I am using ReDim to resize it. I also have a list (think I have it as an arraylist actually but shouldn't matter really) that I would like to hold a pointer to one of the 2d array elements (as well as some other info). The list is a much smaller subset of the 2d array. The reason I am doing this is that the list needs to be sorted based on some data in the 2d array that will be changing. I don't want to have to search through the list each time to update the values as these lists and arrays can potentially be very large.
Maybe there is a better way to handle this but even if there is I would like to know how to simulate pointers in VB.Net. I know there are IntPtr's and references that I could probably use but I have no idea how to do it with dynamic arrays of structures. I'm familair with pointers from C++ but this is the first time I have tried to use (or simulate since there seems to be no real support for them) in VB.Net.
Not sure how clear that was so here are some snippets of the data types involved and some initialization.
Code:
'structures that are in the 2d array
Structure SearchNode
[code]....
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Oct 15, 2011
I'm looking for something similar to using vectors and pointers that I've used before in C++; unfortunately, it doesn't seem like there's an equivalent function in VB.net.What I have is a copy of the array behind a multi-line Rich Text Box, and I need to separate the words from each line (or element of the array) so I can analyze each one separately.In C++ I would do something like this, so I could continuously expand as needed:
[Code]...
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Feb 3, 2012
i am new to commercial programing (and this site) I am currently studding Computer science at a university and i have hit my First roadblock.I am currently developing an application that displays a Table on one Form1 in a Read-Only format and a second Form2 which will only be displayed if after selecting a row on the Grid-View of Form1 you press an Edit button.We are doing that to avoid the User editing the DB in large. The Form2 is populated by a details view of the Table with no controls to change row on the table.What i am trying to accomplish is passing the information of which row was selected in Form1 to Form2 thus making it the current row and subsequently the only one been edited. Currently most things work but as soon as Form2 shows (Form2.show()) it will only display the first row of the database.I want to know if there is a way to "sync" the two indexes.
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Sep 11, 2011
I'm looking to make a simple web traffic sniffer that will automatically reply toauthentication requests from a predefined source, but I'm not entirely sure how tostart/what I am looking at my self here.I guess it's easier to explain if you have a short backstory;I use WebDAV, but Windows does NOT have good support for this (lacking Basic auth support, and Digest support being flawed at best), so you are forced to manuallyauthenticate with a username and password every time you open a file, when you start your computer or a word document (for example) loads resource such as images (imagine writing yoru username and password for every image in a powerpoint!).
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May 19, 2011
have an app where the user can select to search websites I have "Hard-Coded" into the app and select categories and sub-categories to search within those websites.What i need is to figure out how to take a user defined search query (Example: The Holy Bible King James Version), then search the relevant websites (behind the scenes) then output the results something like a google or bing search, then allowing the user to download directly their search query
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Aug 23, 2011
I am in the process of writing a tool to manage DHCP servers using the DHCP Server API. Its an unmanaged DLL so using it is a PITA at least for me it has been.Currently I am stuck trying to enumerate the IP ranges in a particular IP subnet. I am able to access an array of structures but I have only been able to access the first structure in the array of strucutres.Using this I can sucessfully access the first structure in the array.
Dim element_info_array As DHCP_SUBNET_ELEMENT_INFO_ARRAY
Dim element_data_ptr As LPDHCP_SUBNET_ELEMENT_DATA
...
element_data_ptr = DirectCast(element_info_array.Elements, LPDHCP_SUBNET_ELEMENT_DATA)
However when I use this to try and loop through them one at a time it does not work. The ptr returns 0 is null.
Dim element_info_array As DHCP_SUBNET_ELEMENT_INFO_ARRAY
Dim element_data_ptr As LPDHCP_SUBNET_ELEMENT_DATA
For i = 0 To size
[code]....
The sizeof for DHCP_SUBNET_ELEMENT_DATA could be off due incorrectly setting up the union structure for it. I was not sure how it define it so that only the first ElementType and one of the other components is avalible at any given time. It wont even read the first pointer though so that has not even come into play yet.
<StructLayout(LayoutKind.Sequential)> _
Public Structure DHCP_SUBNET_ELEMENT_DATA
Public ElementType As DHCP_SUBNET_ELEMENT_TYPE
[code]....
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Mar 28, 2009
How Should I Use Diffrent Types Mouse Pointers in .Net for Each Form? How Should I Play a mp3 sound File From "D:My Locationsound.mp3"? How Should I Create an Set up File in VB.Net 2008? How Should I Make a Form Shaped Round? How Should I Use The Mouse as Mouse Touch Event?
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Oct 27, 2009
I'm trying to call C code in the form of DLL's from Visual Basic. When I do everything passed by value I have no issues. But what I really need is to return multiple pointers to arrays of sizes I don't know at compile time (so I'd have to dynamically allocate that memory). For instance
[Code]...
Here the array sizes are hardcoded but that's for the simple fact I didn't want to copy my whole algorithm over, in my actual code I wont know the array sizes at compile time. So my questions are these:How do I make the function declaration in Visual Basic 2008? How do I free up the memory in Visual Basic that these pointers point to?
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Jan 27, 2011
My application uses a third party API. This API uses a few functions that returns a value by reference as one of the function parameters. Problem is according to their documentation, the value I am trying to get out of this function is a string pointer.
So if that made no sense, heres an example of the syntax of the function as shown in their documentation:
long ExampleFunction(long ID, long PropNum, char* name, long MaxStringLength)
Input Parameters: ID, PropNum
Output Parameters: name, MaxStringLength
Thats pretty much all the info I've got. Obviously they are not using VB.Net, looks like C to me. I want to get the name output parameter and work with it, but once I get this value, I cant change anything. I know this is because its a pointer (reference type?) but I am still at a loss as to what to do.
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Mar 30, 2011
I had recently(2 months before ) found some code for locking the screen. Here's the link to that code submission in our CodeBank : [URL]
I wish to get a clear idea of what it actually does. As it is a bit advanced code for me.
Here's the main part of the
CODE:
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Aug 15, 2009
I am using these API functions for my project where I am handling 3 unmanaged DLLs of two external apps, basically all it does is to carry data back and forth between these external applications. The project needs a lot of use of pointers, passing pointers and reading/writing to memory so both applications can talk to each other.
Declare Function HeapAlloc Lib "kernel32.dll" _
(ByVal hHeap As Long, ByVal dwFlags As Long, ByVal dwBytes As Long) As Long
Declare Function HeapCreate Lib "kernel32.dll" _
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set of windows API functions for allocating memory, reading and writing to allocated memory, and other required functions to generate required arguments to pass to these API calls?I am up to where I am allocating memory and getting pointer, but I don't know how to go about reading, writing, passing pointers, finding data lengths and reusing memory.
[code]....
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Feb 18, 2009
Correct the problems with this function, and then extend it so that it also returns a usable array of pointers to some structures.
The extended version of this function should: Maintain the same "char *" return type which returns a pointer to a usable, for storing a C string, memory buffer.
In addition, also return a usable array of pointers to structures. This array of pointers is of variable and random length, which must be obtained using GetNumberOfSomeSeqsToGenerate(), which is called, ONLY, from within this new extended version of the function.
The type of these structures and the function that should be used to get these structures are defined as follows:
typedef struct {
char* name; /* '\0'-terminated C string */
int number;
} SomeSeq;
[CODE]...
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Jan 15, 2011
For WD.I = 0
To (WD.Buf.Length - 1)
If WD.Buf(WD.I) = WD.SearchString(WD.II)
[code]....
Multithreading makes the addresses of things much more important with the debugger. Is there a way to get the addresses of WD in VB.net?
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Dec 6, 2009
How can i get all hosts in a LAN and get their mac addresses.i started by getting my host name by this code [code]how can i continue or if there are any tutorials.
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Apr 1, 2010
What I Want Is To Get All The IP Addresses On A Network And Put Them Into A List
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Sep 2, 2010
Im having a hard time understanding how im going to work with this webpage. Im adding addresses to a website, when I click submit either I will get this:
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May 3, 2012
I have a need to collect only IPv4 MAC addresses. Currently I use this Code: But this brings up IPv6 MACs as well. How do I exclude the v6 MACs?
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May 2, 2012
I need codes to get Actives computer names with their IPs ON Lan ?
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