As the reference values are stored in the heap as a data; where do the type information of any reference value is stored?If there are a couple of instances of class Artist; when they are stored in the heap how the .Net tags those memory blocks as type of Artist?
View 3 RepliesIn .NET, integer data type is a value type(stack) and String is a reference type(heap). So If a class A has an integer, and a string type object in it, and a class B creates an object of class A, then how will this object of class A be stored in memory? In stack, or in a heap? This was asked in my Microsoft interview. Need to understand how I fared.
View 3 RepliesI have a storedproc accepts parameters in XMLtype as
CREATE OR REPLACE PROCEDURE GetDetails(
p_para IN XMLTYPE,
[code].....
Assume I have a large dataset and I want to run a "like" function in the dataset eg column - Name..Is there any way to run a like statement in a dataset.Is it possible with ASP.NET? I dont want to run a query to the database.
View 3 RepliesI'm writing a application that has to check live what's going on somewhere. The data is stored in a integer array.But this data comes from a PLC over a COM port. So imagine if someone pulled out the cable while my application is running. I have to find a way that the integer array will be stored somewhere when my application crashes. I thought maybe I could do something with a text file? But how do I get my application to store the data when it crashes? Do I have to surround my whole code with a try catch and then in the catch save everything to a text file? Well I like to know if some of you have better ideas or can point me in the right direction.
View 4 RepliesI am working on completing the Clear event for Button Clear Sub routine. I have been able to clear the textboxes with the code I already have. However, in playing with the application, I noticed that the memory remains stored somewhere in the program. How to both clear the textboxes, and clear the memory?
Code
Private Sub btnReset_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnReset.Click
txtTestScore.Text = ("")
lblNumberOfScores.Text = ("")
lblAverageScore.Text = ("")
lblBestScore.Text = ("")
txtTestScore.Focus()
End Sub
In VB.NET, if I create a class it is a reference-type. But, if that class it chock full of value type properties, how is this handled? If the class is instantied but never filled, I suspect a pointed for to the heap is allocated. But is more space allocated on the stack for all of it's value type properties?
View 4 RepliesI am experimenting with more effective ways to generate forms. My experiments goes into the possibility to link strings, and other types, directly by their class reference and use it to update the original values without any strongly typed code.
I have been using GCHandle.AddrOfPinnedObject to get the memory address of the string, but it gives the the memory address of the string data, not the string class/reference that i need to change to allow me to use this approach.I am aware that strings are immutable and can not be changed (Actualy, you can, but its not recomended), but I do not want to change the actual strings, but change the reference to it (the string object).Is there some other way to get the address of a string object reference?
[Code]...
I have a VB.NET user control that is saving a PDF document and then displaying that in a WebBrowser control. The code looks like this[code]...
View 2 RepliesI'm building SQL statements with a bunch of values from a dataset. Obviously that gives some really long names to put inline or even in parameter. addwithvalue code so beforehand I just declare a bunch of variables with really short names and assign them to the DS's exact fields like: [code] but this way I'm putting all the data in the dataset into memory twice by copying it into a new variable, right? So I was thinking, if it's just a string variable representing a field on the dataset, why not declare it by reference so the variable is basically a handy nickname pointing to that field in the dataset.Will it even work to have a string declared by reference and connected to one value inside of a dataset? And if so, will that stop duplicating everything in memory? I forgot how to declare a variable as a reference to another variable instead of the normal way in VB.
View 12 RepliesLook at this code:
CODE:
My question: When the sub ends the reference to the newReadWorker goes away since it is local to the routine but the worker still runs until it is done. Is the worker disposed of properly when it is done or should I handle the worker better. I am not getting any errors from this design. I just don't want to waste memory.
I've come from a Assembler and C/C++ background, so I understand the concept behind reference types versus value types in vb.net. Also, I've read Jon Skeet's article regarding references and value types and I understand all of that. My question is: How can you tell if a given type is a reference type or a value type? Is it simply that all integral types (ints, floats, etc.) are value types and all classes are reference types? (If so, where do strings fall?)
[Code]...
I have my xslt's stored in a folder in my asp.net web application project folder.
Is there anyway i can call this style sheet from an asp.net web page?
I also.But problem is I generally mug up things for identifying that it is value type or reference type Like class is reference type and structure is value type .. I made a list and paste in my mind .. But of course it is wrong. how to differenciate between value type and reference type by its behaviour or looking at its properties or run time behaviour etc .So that I need not to remember the list..
View 4 RepliesHow to get Hardware properties in VB Express 2010 like video card name and memory type?
View 2 RepliesI'm doing some reading up on the differences between Value types and Reference types - is there any quick/easy way of telling whether a type is Value or Reference? I couldnt see anything in Intellisense so had a look at MSDN pages for a few classes [URL]but it doesnt seem to mention it there either.
View 11 RepliesI've got a class, lets call it Person, which needs to keep some data (in the form of another class which we will call PersonData) in one of its properties - the problem is that I will have several instances of this person class and they all need their own 'copy' of the data (just in memory, its not a file or anything).Hhow would I do this? At the moment because everything involved is a Reference type, I'm assuming that if I were to create 2 instances of my Person classes and assign the same instance of the PersonData class to their properties then when one Person class made a change to the PersonData it would be reflected in the other Person class right? How can I avoid that and make it so that they both have their own version of the data, without having to repeat the procedure that fetches the data in the first place?
I'll explain my exact situation just in case it helps, but this is more of a general question as I could probably get around it in this case by copying the byte array I receive from the server (hopefully that will make sense once you read the explanation below) :
In this case the data I am talking about copying is actually received from a server via TcpClient. The thing is, when the client requests the data from the server over the network, the server has to go off and query several other servers etc so I do not want to be requesting data from the server every single time as that would be a big waste of resources and time. So when a request is made and data is received back from the server, several of these Person class instances will be created (in reality, its a few different classes but that doesnt make a difference for this example) and each need to have access to the full data that the server has sent back but in some cases the Person instances might need to modify the data and this is where the problem appears as they will all be working on the same data.
When I try this, I get the compiler error below:Return TryCast(obj, Double?)'TryCast' operand must be reference type, but 'Double?' is a value type.
This confuses me, I thought that when you make a value type nullable, boxing will be applied - which results in a reference type?
I have a mutable class that I'm using as a key to a generic dictionary. Two keys should be equal only if their references are equal. From what I've read, in this case, I don't need to override Equals, GetHashCode , or implement IEqualityComparer.
View 5 RepliesGetting some errors with a loop. It's a log-in app that has username, passwords & account type stored in a SqlCe database. I would like it to sync with a larger database for updates that has not been made so i left it out but I have started to make a loop that would connect it to the larger DB and if connection failed would try a set number of times before stopping the program. I'm coding this project with Visual Studio 08 pro
Dim conndb As New SqlCeConnection("Data Source = |DataDirectory|\Mydb.sdf")
Dim x, y, z As Double
x = 1
y = x + 1
z = 5
[CODE]...
I m working on one of vb6 projects. There are total 3 projects. One of them is ActiveX Exe is and has main method, second one is also AxtiveX Exe but doesnt have main method (only Classes) and third project is of ActiveX Dll.Well I m trying debug and issue and trying to put all 3 prjts in 1 Group prject but some how I cant add reference of 2nd prject into the first one. I get an error of " cannot be referenced because its project type is exe" but I can add a ref of its compiled exe but this doesnt help in debugging of whole prjt.
View 7 RepliesI'm trying to create a generic function to build a Linq expression from a list of Telerik grid filters. I'm trying to stay clear of dynamic Linq. Because I don't know the type that I'm building the expression for, I'm attempting to use reflection in the lambda functions to refer to a property, but after applying the fix suggested by @JaredPar I get the error, "The LINQ expression node type 'Invoke' is not supported in LINQ to Entities." Is there any way around this? here is my code:
Public Shared Function buildRadFilter(Of T)(ByVal filterExpression As List(Of GridFilterExpression)) As Expressions.Expression(Of Func(Of T, Boolean))
Dim returnPred = PredicateBuilder.True(Of T)()
[Code]....
I have searched for two weeks, every night, exhaustively reading forum threads and trying all suggested solutions no matter how outlandish. Just as is the case with the many many forum threads about this same issue, the site works fine on my development machine. It deploys with no errors. It works from the production server and reads data from the database, but when it attempts to access a profile it crashes with this error.
A number of posts say to check or uncheck an option called "remove app_code.compiled file" but apparently this was a Visual Studio 2005 option. It is nowhere to be found in Visual Studio 2010. A number of posts say to make sure the App_Code.dll is present in my bin directory. It is present. I've deleted the app_code.compile file manually to see if that made any difference. I've changed the target framework from 4.0 to 2.0 and 3.5. I've completely deleted the site in IIS, created a different folder with a different name and redeployed the site with every combination of "allow this precompiled site to be updatable" and "Use fixed naming and single page assemblies".
i've included references to System.Web.Profile and System.Web and System.Web.Profile.ProfileCommon. I've created a new, fresh website targeting .net framework v4.0 and copied that web.config file to my application and recreated my profile entries to ensure that I didn't jack anything up in the config file along the way.
I have a big problem.I'm starting with Visual Basic (2008) and I get this error when you want to run the program,
Warning 2.Unable to load the type library for reference "MSCommLib.Library not registered. (Exception from HRESULT: 0x8002801D (TYPE_E_LIBNOTREGISTERED)) prjRxData
I have an issue with a third-party COM+ DLL meant to be used from VB6, where it has a function to set a Callback for a hardware event. However, I'm using VB.NET, and AddressOf now returns a reference type instead of an integral type, which means that the setCallback function on the COM+ DLL apparently can't be used.
View 1 RepliesAssume I have a large dataset and I want to run a "like" function in the dataset eg column - NameIs there any way to run a like statement in a dataset.
View 5 RepliesIn VB 2005, I am calling a C++ DLL function that returns the address in memory and size in bytes of a jpeg image. How can I load that jpeg image directly from memory into a picture box in my VB form? I cannot afford to save it to disk first.
View 10 RepliesIm getting a problem with one of my programs I have made in visual basic.NET where it gives me a memory error when i debug the program in the IDE. the exact error is this: "Attempted to read or write protected memory. This is often an indication that other memory is corrupt". My program basically has a few forms with text fields on that get their text values from an access database on the same hard drive. Im wondering if im doing something wrong because my program just seems to eat up memory whenever it does anything. For example I have one form that has a combobox on it and when you change the drop down list selection it retreives a few strings from the database and puts them into the relevant text boxes, if you keep changing the selection then the memory usage (in task manager) just keeps going up and up. occasionally I get the error mentioned above when debugging but in my built version of the program it throws an exception everytime the memory usage gets past 49K.
Also I noticed when debugging in the "immediate window" frame I get the following message often:A first chance exception of type 'System. Invalid OperationException' occurred in System.Data.dll...Do I need to somehow be "releasing" the memory that is used to gather data once it becomes redundant?
I am using the following code
This error occurs :
Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
Public Class FormRegEnumValue
[CODE]......................
QuoteSystem.AccessViolationException was unhandled Message="Attempted to read or write protected memory. This is often an indication that other memory is corrupt." Source="System.Windows.Forms"
Im designing a web browser and i continue to receive this error after going to about 3 websites it crashes with that error.