VS 2005 By Reference Variable Memory Efficiency
May 27, 2009
I'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.
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Jan 27, 2012
wondering about the relatively efficiency of declaring oop variables in the loops, emselves, or declaring them before first use. Here are some examples:Declare early:
Dim ix As Integer
Dim currentNode As System.Xml.XmlNode
For ix = 1 To 100
[code].....
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Mar 20, 2009
, I was wondering if it was possible to reference a member of a structure by using a string variable. Here's an example of what i'm talking about:
[Code]....
Now, I know that you would usually reference the value in any of the members by using the following (String1 in this case)
[Code]....
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May 26, 2010
I pass this class i created a variable by reference and i want that reference to be assigned to m_Text so that when i change m_Text it changes the TextValue variable i passed. Example:
Dim test2 as String = "ok"
Dim test as New GeneTextBox(test2)
'then some one changes the text in the GeneTextBox and i want it to change the test2 string...
Public Class GeneTextBox
Inherits Windows.Forms.TextBox
Private m_Text As String
Public Sub New(ByRef TextValue As String)
[code]....
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Feb 1, 2012
I have the following code passing a dataView variable to a function and I am getting the following warning:"Variable 'cl' is passed by reference before it has been assigned a value. A null reference exception could result at runtime."
Function Editclass()
Dim cl As DataView
Bindclass (SqlConnection2, cl)
[code].....
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Jan 25, 2010
I am getting the following error when I call another form from Form1 and fill out the text boxes and Press Ok button. For some reason I cannot access the datatable (dt) from Form1. It gives me the following error: Reference to a non-shared member requires an object reference
[Code]...
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Feb 8, 2010
what is the matter with this
Public Sub showdataset()
For Each dt As DataTable In dsEvents.Tables
Response.Write("<table border='1'>" & vbCrLf)
[code].....
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May 10, 2011
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?
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Mar 15, 2011
I 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]...
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May 25, 2011
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]...
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May 16, 2012
Look 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.
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Feb 9, 2011
The code below works for the class that I hard coded "XCCustomers" in my RetrieveIDandName method where I use CType. However, I would like to be able to pass in various classes and property names to get the integer and string LIST returned. For example, in my code below, I would like to also pass in "XCEmployees" to my RetrieveIDandName method. I feel so close... I was hoping someone knew how to use CType where I can pass in the class name as a string variable.
Note, all the other examples I have seen and tried fail because we are using Option Strict On which disallows late binding. That is why I need to use CType.I also studied the "Activator.CreateInstance" code examples to try to get the class reference instance by string name but I was unable to get CType to work with that.When I use obj.GetType.Name or obj.GetType.FullName in place of the "XCCustomers" in CType(obj, XCCustomers)(i)I get the error "Type 'obj.GetType.Name' is not defined" or "Type 'obj.GetType.FullName' is not defined"
'+++++++++++++++++++++++++++++++
Imports DataLaasXC.Business
Imports DataLaasXC.Utilities
[code]....
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Jul 15, 2009
How can you trace the amount of memory used by each variable, process in a program? I tried CLR 2.0 but am not sure how to read the results. Are there any really good articles on CLR 2.0 that describes what I am looking for?
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Apr 8, 2009
Does a variable create a memory cell, or is it actually the memory cell, for example: Dim Answer As DialogResult
This is the explanation I have written for that line of "This line of code uses a Dim (Dimension) statement to declare a variable called Answer.
This variable creates an object to store the users answer to a dialog result." and this is the explanation that my friend said it was:
"This line of code uses a Dim (Dimension) statement to declare a variable called DialogResult. This variable is a memory cell to store the users answer to the dialog result."
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Jul 9, 2009
I have the following code but I get blue squiggly line in cnn and when i point my mouse pointer on it i see this message "Variable 'cnn' hides a variable in an enclosing block".[code]
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Nov 24, 2009
I am upgrading a very large project from VB6 to VS2008. I have several forms with dozens of combo boxes on each form. I use the same combo box names for each form and want to fill them from a module with different items depending upon the calling form. In VB6, I dimensioned a public variable - FormName as object and called Set FormName = frmMyForm1 on Form Load. In a module, I was able to write the following code:
With FormName
.combobox1.additem("item")
.combobox2.additem("item"
End With
I cannot make this work in VB.Net. When the form loads I call FormName = Me. If I dimension Friend FormName as Object, I get the error message that Public member combobox1 on type MyForm1 not found. If you are attempting to access members on a late-bound object make sure it is declared public". If I dimension Friend FormName as Form, I get an error that says "combobox1 is not a member of System.Windows.Forms.Form".
I have tried both CType and DirectCast to convert the form variable from Object to Form with no success. I also tried creating a public array and storing each form name in it.
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Oct 28, 2011
I am working on a little program (game) is called Pig latin. I created a sub procedure and I passed the word to be converted by value and the piglatin word byref.Now when I call the procedure in the button click event I get the wavy green line under the variable passed by reference but the program works ok. Call Convert_to_Pig_Latin(strOriginalWord, trPigLatinThe error message when I hover my mouse over the green line says " Variable strPigLatin' is passed by reference before it has been assigned a value. A null reference exception could result at runtime."
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
[code].....
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Sep 16, 2011
I'm running VB2008 on Windows 7; I've written out a ver simple piece of code:
Option
Explicit
On
Module
[code]....
When I run or debug the code, it asks for the First Number and then just completes the running of the program without asking for the second number and uses some random number. The console.readline() doesn't work either, the console window just disappears.
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Dec 25, 2011
Class1:
Dim v as integer
public sub storeVar(byval s as integer)
v = s
end sub
[code].....
I need to save a reference of variable s in Class2 in variable v in Class1.(i.e. when the value of s changes v also changes (and vice versa)Is this possible since vb.net doesn't have pointers?Will it work if I change "byval" to "byref"?
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Jun 30, 2010
Such as:
mylist.FindAll(Function(item) item.property = variable)
The reason I ask is if I use syntax like this, I tend to get a string to whatevever conversion error, which makes me think "variable" is being treated literally as a string.
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Apr 5, 2011
I have a class that I would like to link at construction to a given control (say a textbox)
I know I can put a variable into a subroutine referentially but is there a way to store it in the same capacity?
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Aug 18, 2010
I have an application consisting of 2 forms (Form1 and Form2).There is a text box on each form and they are both named Text1.From a sub routine in a module, I want to alter a text box on one of the forms. The sub determines which form to write to and attempts to refer to the form using a variable.But in the example below, gForm never gets declared when it's nested within the If statement.[code]The actual application is not so simple and I need to use this or a similar approach throughout the application in order to reduce code redundancy.To recap, I want to alter a control on a form by replacing the form name with a variable name. [code]
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Jul 16, 2009
[code]...
In the above code i have created a reference to class B from class A. The reference variable "refB" created as a attribute. But i need to encapsulate this reference variable in a property also i need to ensure than instantiation reB = New B() is done even after the use of properties.
1. How do i encapsulate the class reference variable "refB" in property?2. If i hide this class variable "refB" in a property, how do i write the code code initilize "refB" in "A"'s constructor?
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Oct 20, 2009
passing a variable to a sub procedure by reference. Not sure I understand how it works. Here is the code.
Private Sub bntcompute_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles bntcompute.Click
Dim x, y As Double
getnumbers(x, y)
displaysum(x, y)
[code]....
Is the newly modified variable actually being Passed back? and If so where in the statement is it passed back. is it being passed back to the call getnumbers or is it passed back to the statement displaysum?
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May 7, 2012
I have many textboxes that I need to reference dymanically. The controls themselves aren't dynamic, just the way I need to reference them.I've got several text boxes say:
txtMe1
txtMe2
txtMe3
...
txtMe100
I will need to randomly change one of the properties of the edit boxes. So lets say it picks a random number between 1-100 which is 56. So, I would want to change the background of my 56th edit box to:
txtMe56.Backcolour = Color.Gray
The only way I could think of doing this would be to have one giant select case statement to evaluate the random number. But, that is really dirty and not the best peformance wise (this could potentially get called hundreds of times) so was wondering what my options are?I tried to concatenate the random number to my generic control name 'txtMe' but it throws a wobbler. I essentially would want the following to worK:
dim iNum as integer = 56
txtMe & iNum & .Backcolour = Color.Gray
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May 14, 2009
I have a third party dll. I wish to create a variable to reference to one of the variable in it.so that the value in the class change, my value also change. The senario can be reproduce from the code below.For the code below i wish to get the form to display 2 instead of 1. How can i make my variable test2 always referencing test.testValue?
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Sep 15, 2009
is this safe (I know it works, but is it safe)? Is it returning a reference to a local variable, wich falls out of scope as soon as the function returns?
Public
Function myfunc() As String
Dim strXml As String
[code]....
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Jul 7, 2008
Im getting the Variable (Data) is passed by reference before it has been assigned a value error.
[Code].....
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Oct 4, 2009
I'm trying to combine some text and a string value to reference a variable name.[code]
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Feb 25, 2011
I have public variables in a module. I need to get the reference of the variable by using the String name of variable in another formell me how to do this?I need something like the following code:
Dim Var1 As string
Dim sVariableName As String = "Var1"
GetReference(sVariableName).SetValue = "testing"
[code].....
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