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
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)
I've searched a lot on both google and here but sorry, couldn't find.Maybe I'm just asking the wrong question, so I'll try to explain it here to see if someone can help me:
what I'm trying to do is what in C would be as simple as int varptr = &var I have a form that is just a communication watcher/logger. It's just a blank text box with a Pause/Play button and a copy to clipboard button and every new activity on my serial communication is logged. At the moment the form have a timer that once a second do textbox.text = serial1.log ...
but the problem is that I also have serial2; serial3; sql1 that I would like to keep an eye on them, and considering my work here I'm sure I would be re-using this form a lot if I could make it portable. Create one form for each is just stupid, as you'll all agree.
Then I would like to have an sub initialise(byref log as string) that would store this reference into an local variable within the form; so that every new instance of my form could be initialised with whatever log they'll be looking for and the timer just make textbox.text = LogPointer to the actual value of the log string.So, as I said I really wanted a int varptr = &var
Is there a way to write a single function that will control validating the input to any textbox? How to pass control of it.
E.g.: My second try was to: Dim CurrentTextBox As TextBox << Declare a global Write a function that uses the global textbox and takes in 2 parameters, one determining the length it has to validate and the second telling it what to do once the input is verified
Public Sub ConfirmInput(length As Integer, which As Integer) If (CurrentTextBox.TextLength < length) Then CurrentTextBox.BackColor = vbRed GoTo DONE ElseIf (CurrentTextBox.TextLength > length) Then CurrentTextBox.BackColor = vbRed [Code] .....
My first try was to pass a textBox parameter to the ConfirmInput function but I believe that's the same problem as above.
I am in vb.net and have a function that will be accessed by multiple threads. Everything inside the function uses local variables. However, each thread will pass in its own dataset by reference. From what I have read the local variables should be no problem, but I think the dataset coming in is a concern. How should I control access / execution of this function to make sure that it is thread safe?
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)
So strings are reference types right? My understanding is a reference to the string in the heap is passed even when you pass the string ByVal to a method.
I want to pass a List of T where T is an object I've created that has about ten properties (strings, dates and integers).The lst passes to the function successfully. I am also passing an New T of the Object (itm as T).I can see all the values (see image below), but because it's generic I cannot seem to retrieve the property values and I cannot figure out how to iterate through the properties of each itm as they are retrieved in the For Each.[code]
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"
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.
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"?
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.
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]
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?
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?
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
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?
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
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"
In vb.net 2005 how would one referance a control as variable and change it"s properties. Such as in control X visible = True. Tryed string manipulations that did't work.
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.
How does the GC dispose objects created in the following 2 scenarios?
1)
Private Function DoSomething() As Boolean Return New DatabaseManager().Insert() End Function
2)
Private Function DoSomething() As Boolean Dim mngr As New DatabaseManager() Return mngr.Insert() End Function
In Option 1, I don't create local variable to hold the reference of the object. In Option 2, I hold the reference in local variable.What option is better and why? (if any)
I've been trying implement Constructor method in passing variable between two forms.Just a rough user interface guide - issue Invoice. User would type in all the Customer Name, Document Number. Once he reached Item Details, a Child Form would pop-up for the User to select/search the Invoice's Item; Once selected, the selected item would showed in the primary Form.
What I had tried is, the Constructor method worked perfectly when it is self-contain in a new project, yet to be implement in my application.But when I implemented, there is an error: Reference to a non-shared member requires an object reference.
