C# - When Variables Defined In The Inner Scope May Be Garbage Collected?
Sep 28, 2009
If I want to narrow scope of a variable in C#, I can introduce additional braces - i.e.:
class Program
{
static void Main(string[] args)[code].....
In the ide, I can no longer reference y outside of the scope introduced by the new braces. I would have thought that this would mean that the variable y would be available for garbage collection.(it is interesting to note that when viewing the compiled code using reflector it appears that there is no difference with or without the additional braces)Is there any way similar to this to narrow scope when using VB.net? Does this have any impact on when variables defined in the inner scope may be garbage collected?
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Jun 6, 2012
I am using vb.net 3.5 and application is interacting with VC++ dll.
code is:
Public Delegate Sub delProcess() //Globaly declare
im del As New delProcess(AddressOf Process) //Process is function which not returning
[code].....
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Jan 7, 2010
Does the memory used in declaring variables are reclaimed by the OS when these variables go out of scope?Does the memory used be released by setting thier value to nothing? if not, then how can I force the garbage collector to run or excecute at a certain/desired time..How about in Windows Forms..How can we make sure that the memory used in initializing and showing forms be released if those forms were closed?
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Feb 21, 2012
I've been doing some reading on garbage collection in .NET and I was hoping for some clarification. So, as I understand it if I declare a public shared class variable, the GC will never get rid of it. Is this correct?Also, what then of private variables? Take the following example:
public class myClass
private shared myString As String
public sub ChangeString(newString As String)
[code].....
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Jun 11, 2012
I'm working with legacy data, which often brings me one information splited in multiple columns. I'm trying to reproduce the following SQL query.[code]This own statement will run into the following exception:Variable 'line' of type 'SomeTable' referenced from scope '', but it is not defined. Any directions? I'm trying to avoid magic strings, but I'm always giving up to it (as using HQL the concatenation expression + like function works like a charm).
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Jul 31, 2010
Are the following three the same upon compilation
dim x as new assigningfunction
dim x as new assigningfunction()
dim x as assigningfunction = new assigningfunction()
[code].....
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Sep 12, 2009
I have a VS 2008 C# application that I'm converting to VB 2008.
This statement in C# works as I expected:
IPAddress IPAddr = new IPAddress(0xFFFFFF0A);
IPAddr has a value of 10.255.255.255.
However, in VB this fails:
Dim IPAddr As New IPAddress(&HFFFFFF0A)
with invalid argument (the parameter of IPAddress should have type Long).This also fails:
Dim Addr as Long=&HFFFFFF0A
Dim IPAddr As New IPAddress(Addr)[code]....
does not produce a value of 4294967050, but -246. It appears to have defined a .net type of Int32, not Int64.How do I declare an Int64 variable in VB using a hex constant?
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Jun 13, 2012
That question sounds maybe a little confusing so I'll try to explain it with an example.[code]...
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Mar 1, 2011
I 'm working on a quite large VB application, and recently I started profiling the memory usage, because there were some issues with objects not being collected.I noticed that the SplashScreen (boilerplate SplashScreen hooked up via Project Properties) never gets collected, because is remains referenced by My.MyProject.MyForms.m_SplashScreen. This is apparantly a private member, and I can't figure out how and where to set it to nothing with reflection code.I looked into my code to make sure i'm not doing anything special; I don't even reference the form anywhere.
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Jan 7, 2011
I have a txt file comprised of a vertical list. The list contains x-amount of groups but what is standard is that they are always made up three entities.Example as follows:
PANNEL A
38
2440
Explained as:
NAME
WIDTH
LENGTH
A list of three items (though list can contain x-amounts) is identical to:
NEW BEAM
38
2440
[code]....
I now need to create a new txt file, which is written as follows:
("NEW BEAM" is "38" x "2440")
("WOOD" is "22" x "610")
("ITEM A" is "50" x "1220")
How van I do this using VB.NET?
+
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Jun 14, 2010
I have this app that can now control my browser but after I use the htmlcollection of links how can I put that stored information into a richtextbox?[code]
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Jun 4, 2011
I have a grid of RadioButtons, and need some help in Check / Uncheck acording to data collected from a .txt file.
The .txt file contains a list like this:
A01,a
B01,b
C01,c
A02,a
B02,b
C02,c
I have set up in a grid formation RadioButtons, and named them A01,B01,C01,A02,B02,C02. I have loaded the .txt file in an array, and want to use the first 3 letters in the array to point to the RadioButton.
Problem: How do I get the string "A01" from the array to point to the RadioButton control?
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Apr 20, 2012
I am currently working on a Database that collects information. Firstly, i use a new windows form to collect that data. I have it set up to where, when the form loads, the database is ready to collect the information fields. And then the form closes on the button click to add that data, it does not update that data table view. It adds it once i close the program and debug it again.
Code: (Open the windows form)
Private Sub btnAddNew_Click_1(sender As System.Object, e As System.EventArgs) Handles btnAddNew.Click
AddNewClientData.ShowDialog()
[Code].....
Problem two: I need to make a button that will increment a cell that was set as an Int, by one, but can't figure out how to put it into code.
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Dec 29, 2011
I am trying to redirect command line output to a list box in a vba macro, and I've found some code that I think might point me in the right direction, but I keep on getting the same error. When I use this code [code]It gives me the error in the title and highlights the first declaration line.What does it take to define a new "process".
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Aug 12, 2009
I have a requirement to move the html text available in a string builder to a word document and open the word document after the data is appended in a VB.NET console application. I am new to console applications and am not sure how this could be done, but I am aware that if I am using a Web Application then I can use the following code:[code]
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Mar 9, 2012
I've heard that the c# garbage collector can be 'more aggressive' than it's vb.net counterpart. Is this true? Are there any other differences in how garbage collection is run in vb.net vs. c#?
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Jun 15, 2009
I'm trying to introduce delay to my code so that it would read in the noise or garbage data.
I'm receiving the data from RFID to pic thru RS232.Is there any simple delay that i can use? I seriously don't understand threading.
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Jul 23, 2010
I thought that when a variable went out of scope (like a variable declared within a method - when you exit that method the variable is out of scope) then it was eligible for garbage collection and when it was garage collected the Dispose method is called on it. Now I know that it does not get disposed immediately but I assumed it would be basically as soon as the process starts to take up quite a bit of memory.However, I found that my app's memory usage seems to constantly increase when I dont manually Dispose of a specific method local variable. Of course its good practice to call Dispose and ordinarily I would but I just didn't realise that this particular class actually implemented IDisposable. The class in question was the System.DirectoryServices.SearchResultCollection class, and I was looping through the items in it like so:
[Code]...
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Dec 4, 2010
I have a function like the following: Public Function testFunction(ByVal input_string As String) As String
[Code]...
or just let the garbage collector do the job for us? Both the above functions work, but I want only know the best practice for performance...
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Jan 11, 2011
I'm creating a windows forms program and have recently noticed a large amount of memory slowly being eaten by the application. I went through my program and tried to tie up as many loose ends as I could in relation to object creation but noticed that the program would still keep memory for every form loaded until it eventually crashed.
I decided to make a simple test program which sole purpose is to pop-up a new form with a few controls, wait for 200 milliseconds, then close the form and repeat the process 30 times every time I hit a button. I found it caused the same behavior, even with the only new object creation being that of the form. So, I decided to manually invoke the garbage collector in a subroutine which handles the formclosed event. During tests I would get some memory back occasionally, but not enough to make a difference in the long run. So I start setting the form variable to nothing before I called GC.collect(). The program will initially eat a few 1000K of memory before leveling off and using only 20-40K for every 30 forms created.
Now what I'm wondering is, what is the point of an automated garbage collection system if it requires constant manual evocation and explicit dereferencing of all new objects to be effective? Have I completely lost grasp on the scope of VB.Net forms and it simply never marks forms as available memory to be cleared?I would have thought object memory references created within a form would be marked as usable when the form's close or dispose routine is called and no references to objects created within the form exist anywhere outside the closed form.
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Sep 22, 2009
I am trying to create radiobuttons, and then create code for them after they are created. I have the code to create the radiobuttons. What I want to do is create a sub for the event of changing the check value for the radiobutton. Or to have the check value recognized by a button click. For example, you click the button and if the first radiobutton has the circle filled then a msgbox comes up and says hurray. My code so far is this:
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Nov 2, 2010
I am using a function from a dll in unmanaged code that requires a callback to my managed code in Visual Basic 2010. The callback is asynchronous and is called continuously over the life of the application. What's the best way to protect the callback function from the garbage collector? Right now it is being collected after several dozen calls from the dll.
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Mar 2, 2010
I'm using following code to receive content of a ListBox
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Oct 5, 2010
I have a callback function in a C+ dll:
<UnmanagedFunctionPointer(CallingConvention.Cdecl)> _
Public Delegate Sub DeviceDetectionEvent(ByVal YasdiEvent As YASDIDetectionSub, ByVal DeviceHandle As UInteger, ByVal param1 As UInteger)
[code].....
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Jan 29, 2009
Is the memory from primitive data types (int, char,etc) immediately released once they leave scope, or added to garbage collection for later release?
consider:
For x as integer=0 to 1000
dim y as integer
Next
If this doesn't add 1000 integers to the garbage collector for clean up later,how does it treat string objects? would this create 1000 strings to clean up later?
For x as integer=0 to 1000
dim y as string=""
Next
How about structures that contain only int,string,etc... data types?
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Oct 25, 2010
with VB.NET + MySQL i am having a connection object which is public public MYcnn as MySql.Data.MySqlClient.MySqlConnection when my main form opens MYcnn will open & will be available for all the procedures & functions. i never close this connection until the last form of the application closes (yes of course i compromise of some security + performance issues)
my problems is(1)when & how the garbage collector works to collect my connection object if my connection object remains open for > then certain time(2) how to offer or fix the time of my connection object availableness to garbage collector (3) i would like to write an event for the connection object closed event(i am explicitly declaring the connection object)
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Nov 26, 2010
I have an Excel file that downloads automatically, but for some reason the binary XLS file contains some garbage HTML text at the end of it.
When opening the file in the Excel application, it shows a warning but proceeding will automatically remove the garbage HTML text.
However, I need to open the file programmatically. When doing so via
Dim wb As Workbook = Excel.Workbooks.Open(ExcelFileName)
It throws:
Exception from HRESULT: 0x800A03EC
a) Get Excel to perform a similar action as if I manually opened it and remove the garbage HTML automatically. NOTE: Tried setting the XlCorruptLoad.xlRepairFile parameter and it didn't work.
OR
b) Remove the garbage text from the XLS binary file (FileStream?) and resave it before attempting to open the file with the code mentioned above.
The garbage html always comes at the very end of the file and starts with
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Oct 6, 2009
Datatable object within class function + garbage collection?
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Jun 21, 2010
[Code]...
a messagebox appear that show user-defined type not defined i had try another code but it still same error.. i'm using vb6
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Feb 8, 2011
Here's the scenario, winforms application, monitoring via Task Manager Processes Tab.On initial launch spins up to ~61,000K (initial data grid and data loads)If I minimize the application, not touching or doing anything the Mem usage drops to 1,380K.When I restore the application is spins back up to only 5.8K
So my question is, does the minimize send some internal message to clean up resources since the application in question is not in focus?The first app I noticed this in happens to be VB.NET, but I've observed the same behavior in my main C# winform applications.
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