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How the memory is allocated in heap for a dynamically growing List.
while creating a new object the number of bytes required for that type is allocated in heap. How this is working if that class has a dynamic list???
My small attempt...
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a List does not store its items, all it stores are references to those items. Basically it stores them in an array. When the array gets full, a new array is allocated, twice the size, and its content (the references!) is copied to the new array.
Objects never grow. They have a fixed size in memory. Assuming Car and Wheel are classes, when a Car object has four Wheel objects, it holds 4 references to those Wheel instances, which are separate objects. If Wheel where a struct (hence a value type, not a reference type), the Car would hold memory to store 4 Wheel instances all the time, whether you initialize them or not.
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It is like a linked list(not really.. but for the memory allocation part). It can have any number of items while memory is free. It is like using malloc function
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pranav95 wrote: It is like a linked list
Not at all. A linked list would consist of individual items, each holding one or two pointers to its logical neighbors, and would imply: a separate memory block for each item, no overall memory requirement (except maybe for a head node and a tail node), and certainly no memory requirement larger than the item size itself. A .NET collection is based on an array, most additions do not require any memory requirement at all, and the array's capacity grows by doubling it, which may cause it to become located in the "large object heap" and may even cause fragmentation and out-of-memory situations one would not have with a linked list; OTOH being array-based has advantages, e.g. it allows for an O(1) indexing.
Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]
I only read formatted code with indentation, so please use PRE tags for code snippets.
I'm not participating in frackin' Q&A, so if you want my opinion, ask away in a real forum (or on my profile page).
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according to my current knowledge in .net memory management the value types are stored in stack and reference types are stored in managed heap.
Form this, its clear that the object of a class will be saved in heap. Then where will be the memory allocated for the value type member of that class??
My small attempt...
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The entire object will be stored on the heap including any 'value type' members.
It's time for a new signature.
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For a method's local variables, value types are indeed stored on the stack and reference types on the heap. Reference types are a little confusing, however, because they are really stored in two parts: the reference, which is stored on the stack just like a value type, and the 'body', which is stored on the heap.
Now, lets look at the body of a type (reference type or value type). Reference types and value types can have fields of both types. The fields of a type are (effectively) concatenated together. So the body of a type is the concatenation of the contained value types and the references to the contained reference types. And this body is 'a chunk of memory' which is stored somewhere - on the stack (if its the body of a value type), on the heap (if its the body of a reference type) .. or nestled inside the body of some other type (if its a field in another type).
So, it may be more useful to think of value types as being stored 'where they are declared' instead of thinking of them as being stored on the stack, while reference types have their reference stored where the variable is declared, and its body is always stored on the heap.
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Hi
As i was preparing to deliver my first software (VB.NET 2.0/Access 2003) I noticed the folder containing the database is published separately from the set up file. i browsed it and realised all i needed to do was remove the .deploy extension added by vb to the database file and, voila, i had the access database visible and opening like it was not even part of the software.
My assumption was that it should be locked inside the software set-up, which is not. Does anyone know how to hide the database so that users cannot just find it and open it? How come i have never see the database that runs Ms Word, for example?
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cyberexel wrote: As i was preparing to deliver my first software (VB.NET 2.0/Access 2003
Which version of VB.NET?? I'm assuming you're talking about .NET 2.0.
cyberexel wrote: My assumption was that it should be locked inside the software set-up
Wrong. Access is a file-based desktop database.
cyberexel wrote: Does anyone know how to hide the database so that users cannot just find it and open it?
Impossible. Since it's always a file, and users have the ability to show hidden files, you can't really hide it at all. The best you can do is password protect it, but then there's always the utilities sprinkled throughout the web that will break that.
cyberexel wrote: How come i have never see the database that runs Ms Word, for example
Because there's no database that runs Word?
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Thanks so much, Dave. Your straight answer really saved me time searching for things that are (almost) not published, yet!
If you could:
1.Is it possible to use Access 2007 and have vs 2005 'see it' as a datafile? ie when i published my application with accdb database vs did not put it in the bin directory even if i manually put it there. also when i checked in the application files in project properties it is not listed as a datafile as i expected/thought. which means set up will not find it and connection strings are lost on installation.
2.I opted for Access 2007 because some searches indicated that it is nearly unbreakable. How true is that, and would you recommend me on vs 2005 & Access 2007; or vs 2010 and Access 2007? I haven't yet bought vs 2010 and it is quite expensive!
3. mine is a small application that i want to give to 100 users. i want to save them process of installing sql express (the reason for access 2003/7 instead of sql 2005 express). am i thinking right? if I attach sql express database as file (ie to avoid use of servers), will i have a way of protecting the database when installed on users computers?
4. i see software like firefox come in 'one file', not several files as mine does when published. How is this achieved? Is it possible with my vb 2005 (access or sql) applications?
thanks.
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You seem to be under the impression that all applications require databases, and this is not the case. Take Word for instance - files are saved out as Compound OLE Documents; no database in sight.
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cyberexel wrote: 1.Is it possible to use Access 2007 and have vs 2005 'see it' as a datafile?
The version of Access doesn't matter. A database file is still going to be a database file, independant of Visual Studio. Your code uses it the same way, no matter which version of VB.NET or Access you use.
cyberexel wrote: vs did not put it in the bin directory even if i manually put it there
That depends on how your code is written, specifically, the connection string. Since you're a beginner, I'm assuming you're using the designers for everything database related. If you're using ClickOnce deployment, your database will go into a different folder, seperate from the application, usually referred to as the |DataDirectory| folder.
cyberexel wrote: 2.I opted for Access 2007 because some searches indicated that it is nearly unbreakable.
Only for a short time. Any password can be broken, it's simply takes time.
cyberexel wrote: would you recommend me on vs 2005 & Access 2007; or vs 2010 and Access 2007?
The version of Visual Studio doesn't matter.
cyberexel wrote: 3. mine is a small application that i want to give to 100 users. i want to save them process of installing sql express (the reason for access 2003/7 instead of sql 2005 express). am i thinking right?
I don't use Access for anything any more. For a desktop database, I always use SQL Server Express. Access has too many limitations and quirks for my taste and doesn't support stored procedures or a full SQL implementation.
cyberexel wrote: will i have a way of protecting the database when installed on users computers?
You have no way of totally protecting any database. It's simply too expensive to take all the precautions of trying to protect users from themselves. If they want to get into the database and screw with stuff, they're going to get into it. When did you become their parent??
cyberexel wrote: 4. i see software like firefox come in 'one file', not several files as mine does when published. How is this achieved? Is it possible with my vb 2005 (access or sql) applications?
FireFox is a web browser, not a database, nor does it use one. Your app uses a database, which has to be stored in a seperate file from the .EXE. Not all applications use a database, which is what I think your misconception is.
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Thanks a lot! I have learnt a lot from you. I really appreciate.
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can any body plz send combox selected index changed code
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void comboBox_SelectedIndexChanged(object sender, EventArgs e)
{
}
comboBox.SelectedIndexChanged += comboBox_SelectedIndexChanged;
DaveIf this helped, please vote & accept answer!
Binging is like googling, it just feels dirtier. (Pete O'Hanlon)
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
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Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
'What You Want To Do
End Sub
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thanks for your reply pranav.
i done this in web application it works fine but it is not worinking in windows application
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Try the SelectionChangeCommitted Event or SelectedValueChanged Event
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Don't report the same question. Edit your original if necessary. Delete the previous post
And, do not ask for code.
I know the language. I've read a book. - _Madmatt
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mark, thank you very much for your suggetion,
i always wellcome to listen my mistake.
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i worked on web page selected indexchanged in asp.net it works fine
but when it comes to windows app it is not working.
can any body plz explain the code of combobox selected indexchanged.
prashanth
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From my knowledge CLR is a set of DLLs. In which language CLR is Written?
My small attempt...
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Jinal Desai - LIVE wrote: It is made from set of DLLs (Assemblies).
Have you even read some of the information you have posted links to?
You claim that CLR is set of assemblies, which is completely wrong.
There's significant difference between assembly and dll.Each dll is not assembly and each assembly is not a dll.One of the links you posted claims that CLR is an equivalent of JVM.Are java frameworks part of JVM?When we are talking about CLR we mean MS runtime for running managed code, we don't mean mscorlib and the other assemblies.
Life is a stage and we are all actors!
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