Memory Used In Declaring Variables Are Reclaimed By The OS When These Variables Go Out Of Scope?
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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Mar 23, 2012
I define some global variables of a class as follows:
Private Class MyClass
Private var1 as Decimal
Private list1 as List(Of string)[code].....
But I found that after this form is closed, all above variables, var1, list1, list2 still exist in memory. I thought they should be collected by gc since the form is already disposed as I confirmed.
Add: I have monitored half an hour after the form is closed. But these variables are not collected by gc. I have an automatic update procedure on the form which uses above variables.Since the above variables still hold values, the automatic update procedure is always called which causes exception. (One quick fix is to check if form.isDisposed in update procedure. But I do not think this is elegeant. Besides, these variables occupy memory.)
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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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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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Jul 26, 2010
I actually came from VB6 and starting to learn VB.NET. I saw this line of code which I cannot understand how it works nor how it goes.
Private MAX_VALUE As Integer = (1 << 14)
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Oct 6, 2011
I have just been experimenting with nesting classes within a User class I had already created.
E.g.
Friend Class User
[Number of Properties...]
Friend Class Address
[code]....
I get the same error message!!! "Declaration expected". Also I notice the variable's name is not coming up in intellisense. I have not come across this before as declaring an using variables and objects has been straight forward up until now.
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Sep 29, 2011
The user clicks a button, a new form is generated where the user enters his/her password? How can I keep an in-memory copy of the username?
For instance in web forms, I can just use Session ("User"). How can I replicate this with winforms?
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Sep 23, 2011
I've created a 30 point wizard. Every step gathers between 1 and 3 variables. I've created a module and publicly declared the variables there. At the end of the wizard, one master form opens, gets all the variables, and displays them on one form. At this point calculations are run too which populates more variables. This works fine for one instance of the process.
the user may want to be running two instances of the wizard at once. Obviously, if the previous wizard is part complete and they start a new one, the variables are going to get crossed or replaced by the new wizard.Is there a way for the variables to be declared publicly but used in multiple instances?
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Oct 25, 2010
OK, I'm working on a project and i need to access the property of a usercontrol which I have set.Here is the code in the UserControl
Private Color As Color = ColorTranslator.FromHtml("#000000")
Public Property InkColor() As Color
Get
[code].....
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Mar 5, 2010
What's the proper way to declare variables in a class? I've been doing something like:
'in a class
public shared teststring As String = "first"
'on a code behind
[Code]....
with shared variables loading a second window or reloading the page (without clicking the button) renders the hello world string. so how do I declare variables in a class but make it per instance?
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Oct 15, 2009
When I am writing a sub or function that does some calculations etc. I often need a loop or a integer variable to count.
An example:
''' <summary>
''' Compare elements with the new data and perform all necessary actions.
''' </summary>
[Code]....
As you can see, variables like timespan, nullCount and seconds are declared within this sub.
My question is, is it better to declare these in the class? I can imagine that would boost performance.
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Jun 25, 2011
Sub Application_Start(ByVal sender As Object, ByVal e As EventArgs)
Dim chatters As List(Of Chatter) = New List(Of Chatter) chatters.Add(New Chatter(New Guid("CD863C27-2CEE-45fd-A2E0-A69E62B816B9"), "Me")) chatters.Add(New Chatter(Guid.NewGuid, "Juan")) chatters.Add(New Chatter(Guid.NewGuid, "Joe")) Application.Add("Chatters", chatters)
[code]....
I am unable to understand last 3 lines that are bold and underlined. Please what is hppening here. Chatter and Chat are two classes defined in App_Code folder. Is there any sight that contains all possible ways to declare and initilaze variables and data structure:
Dim chatters As List(Of Chatter) = New List(Of Chatter)
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May 11, 2009
I need to write a simpe calc. program to add, mutiply, subtract and divide. I want to have two textboxes that I enter numbers in and when I click a button, +,-,/ or * a third text box will display the result.Rather than declaring my variables inside each instance of a click event I would like to declare them globally so I just need to perfom the calculation on them and display result. However declaring them globally doesn't work for me. I;ve tried the variables inside the btnAdd click event which works, but as I said I'd prefer to declare them onece globally.
Public Class Form1
Dim number1 As Double = CDbl(txtNum1.Text)
Dim number2 As Double = CDbl(txtNum2.Text)[code]...
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Dec 8, 2009
recently started converting our project from 1.1 to 2.0
It was fine with the following:
Public ghtAllAppMsgs As New Hashtable(300)
Now it is complaining to change to the following is this the right way:
Public ghtAllAppMsgs As New System.Collections.Hashtable(300)
This is under global.vb class file: here are the imports i already had in this file:
Imports Microsoft.Web.UI.WebControls
Imports Microsoft.Web.UI.WebControls.MultiPage
Imports System.Web
[Code]......
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Mar 23, 2012
I am writing a program and i need to declare matrices but there will be a different number to declare everytime the program is run so I was wondering if anyone knew how to declare them inside a for loop
eg.
For i = 1 to NumberOfMatrices
Dim matrix i (5,5) As Double
Next
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Feb 11, 2009
I am new to the forum and new to the visual studio set up and have been working at a practical at home and have ran into some difficulty. The notes say that I am to declare several module variables below the section entitledI have the rest of the form complete but have been unable to locate where I am to place this code
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Nov 5, 2010
I am at a loss to figure out why this code results in 2 errors when I try to Parse it inthe SSMS.
@Collection varchar = Books,
@Title varchar = 0,
@Authors varchar = 0,
[Code].....
I think that I re wrote this query ten times todaday and continue to get errors and don't know what my problem is
There are underlines in red under the 0 in the BookLoanStatus and under all of the parameters in the SQL.
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May 26, 2010
I am new to Visual Studio.NET but very familiar with the old ASP (using DreamWeaver).I am unfamiliar with this system of having seperate files for VB code and HTML, in my Visual Studio project I have a Default.aspx file and a Default.aspx.vb file. Now I want to declare a variable that will be accesible to all my functions on the Default.aspx.vb file. I.e. if a user clicks on one button and it launches a Protected Sub called Button1_Click, I want that button to be able to read or write to that variable and then if a user clicks on another button, I want it to likewise be able to read and write to that variable.So where should these variables be dimmed?
At the top of the aspx.vb file? Before or after the line that says "Partial Class _Default"?Or at the top of the aspx file? (Within <% %> brackets?)
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Jan 6, 2011
Is it possible for a class of exposing a type for function returns, without allowing users of that class to create variables of that type? A couple usage scenarios:A Fluent interface on a large class; a statement like "foo=bar.WithX(5).WithY(9).WithZ(19);" would be inefficient if it had to create three new instances of the class, but could be much more efficient if the WithX could create one instance, and the other statements could simply use it.A class may wish to support a statement like "foo[19].x = 9;" even when foo itself isn't an array, and does not hold the data in class instances that can be exposed to the public; one way to do that is to have foo[19] return a struct which holds a reference to 'foo' and the value '19', and has a member property 'x' which could call "foo.SetXValue(19, 9);" Such a struct could have a conversion operator to convert itself to the "apparent" type of foo[19].In both of these scenarios, storing the value returned by a method or property into a variable and then using it more than once would cause strange behavior. It would be desirable if the designer of the class exposing such methods or properties could ensure that callers wouldn't be able to use them more than once. Is there any practical way to accomplish that?In formulating a question, it's difficult sometimes to draw the line between complicated usage cases, and simpler usage cases which aren't quite so important. Here's another usage case, and one closer to the one I'd be most interested in (though I'm also interested in Fluent chaining; being able to have something behave like a C++ reference to a value type would be nice, but probably too much work to bother with).I have a type which is somewhat like the Windows registry, in that it is a hierarchical collection of items, each of which may have a string value, an integer value, and/or a nested collection of items. I wish to be able to support the following types of usage:[code]As for the Fluent interface, my thought would be to have the WithXXX properties return a new instance of a derived class which shadows (not overrides!) the WithXXX properties with versions that simply modify the current instance. The return object from WithXXX would be known to be of the derived class, and would thus use the shadowed WithXXX methods, but once it was assigned to a variable, it would be regarded as an instance of the base class, so the next WithXXX would create a new instance.
C++ a stronger concept of value types than C# or vb.net, including the very useful concept of references to value types; it ensures that references to value types cannot be persisted outside the scope of the type in question. Unsafe code in C# can use pointers to value types, but they don't have the protections offered by C++ references.
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Feb 7, 2012
I'm wondering about the performance differences between imports and inherits in a .net app.I currently program by creating multiple classes that logically define my objects. e.g. a class for customers, users and product.When i want to use these classes in a page i have to import them eg. "Imports Custmomers" and then later in my code i have to create a variable and datatype it before i can use the sub routines and functions from class.I understand from a coding perspective this keeps it all neat and tidy.So my question Would it be not better to combine all my classes into a base class, inherit that base class, rather than import it, when i want to use it and so cut down on the extra declarations and associated code that come from importing a class; and if i did this would it aid performance?
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Apr 20, 2011
how can i make sure i dispose of ALL my variables and sessions when i close the application?
i already have session.abandon(), but does it still keep all the other objects stored somewhere in the memory?
i've noticed that my w3wp.exe process keeps going up as i am testing my application. what is a good way to keep mem usage under control?
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Dec 7, 2010
I wanted to know if u define a dimension in a function or subroutine and that func/sub is called say 5 times, does the memory new block of memory get assigned to it every time the func/sub is run or does it use the one it got assigned the first time?
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Dec 11, 2011
Last year (2010) I came across a FANTASTIC command that allowed me to take a string of variables with a common delimiter and break it all back out into separate variables (possibly an array) with one statement.
[Code]...
As long as the delimiter was a unique specifiable character, this one-statement command could break it out into elements. my memory and point me in the right direction.
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Sep 27, 2010
I have code, shown below, that works all except for 1 thing: The variables being passed byRef get passed, but once modified in the else section of the "if me.invokerequired" code of RecordData, the variables are never updated in the calling function. To reiterate, the calling function does not receive the updated data that is in the variables custid and amt.When debugging, I see the data change in the else section of "if me.invokerequired", but once it returns from the callback the data is missing.[code]
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Mar 8, 2011
Question 1: What is the difference between "Background Worker" and "Worker Pool" as indicated within the MSDN samples provided.
Question 2: I noticed while using, AddressOf _Function_, variables cannot be passed; what would be an efficient solution to this?
Question 3: While using multithreading is it required to invoke before setting variables, or only form properties?
Question 4: While using System.Net.Sockets is it safe/efficient to use Application.DoEvents while waiting for new data; or would be using a Do While loop be fine without DoEvents since the action would be multithreaded? Note: there can be up to 2000-3000 sockets in use at a time.
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Jun 9, 2012
I'm new in .NET programming.I have a class Form1 that includes Button1_Click event.Button1_Click creates a multiple Text Boxies at run time)Here is the class:
Public Class Form1
Dim shiftDown As Integer
Dim counter As Integer
[code].....
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Apr 16, 2010
What is the impact of creating variables using:
Dim ds as New DataSet
ds = GetActualData()
where GetActualData() also creates a New DataSet and returns it? Does the original empty DataSet that was 'New'ed just get left in the Heap?
What if this kind of code was in many places? Would that affect the ASP.NET process and cause it to recycle sooner?
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Dec 14, 2009
I have text for example:11.12.2009 or 7.8.2004 and how to get three variables, a, b, c
a = 7
b = 8
c = 2004
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Jul 10, 2011
Is it in VB.NET possible to use variables without the need of use DIM? Now I have to use the variables like this:
dim a = 100
dim b = 50
dim c = a + b
I want to be able to use vars in this way:
a=100
b=50
c=a+b 'c contains 150
I think in VB6 and older VB this was possible, but I am not sure.
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Feb 6, 2012
This is the updated code:
sql = "INSERT INTO Strings (String_Name, Long_Text, Short_Text, Alternate_Text, Multi_String_ID, Lang_ID) VALUES (?,?, ?,?,?,?)"
Dim command = New OleDbCommand(sql, pConn)
command.Parameters.AddWithValue("@webStringName", "String_Name")
[code]....
I am trying to create and INSERT statement with and OLE adapter. I had it working without paramtersm but now I am trying to add parms and am having issues with the syntax.Here is the code so far...
command = New OleDbCommand(sql, pConn)
sql = "INSERT INTO Strings (String_Name, Long_Text, Short_Text) VALUES (?,?, """ & ptsShortText & """)"
command.Parameters.Add("@webStringName", OleDbType.VarChar, 250, "String_Name")
command.Parameters.Add("@webLang_String", OleDbType.VarChar, 250, "Long_Text")
[code]....
Was just trying to get the first two variables parametrized.
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