C# - Define A Variable Of Different Types?
Feb 8, 2011
i wonder if it's possible to define a variable/property of more than one type. Let's say i want a property TextWebControl that is a WebControl and also implements Web.UI.ITextControl(f.e. like a TextBox or Label). But i don't want to enforce that it is a TextBox or Label, but only one that inherits from WebControl and also implements ITextControl so that it also would work with controls added in future releases of .Net-Framework.
.Net-Framework 4.0
Edit: I have retagged the question and added VB.Net because it's my default language. Normally it's no problem for me to understand C# also, but i must admit that it's difficult to translate generic stuff to VB.Net without experiences and it's also better documentated in C# than in VB. So i would appreciate(and aceept) a working example of a VB.net generic type of ITextControl/WebControl.From Marc's answer i understand that i need a generic class. But how do i instantiate it in SomeClass? This won't compile:
Class SomeClass
Public Property info As InfoControl(Of WebControl, ITextControl)
End Class
Public Class InfoControl(Of T As {WebControl, ITextControl})
End Class
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May 4, 2011
Is there any way to define a Generic in VB.NET which will accept only Singles or Doubles? I tried the following things, based on what I've found online, but none compile:
Dim target As Nullable(Of {Single, Double})
Dim target As Nullable(Of T As {Single, Double})
Dim target As Nullable(Of T {Single, Double})
Dim target As Nullable(Of Single, Double)
Dim target As Nullable(Of T As Single, Double)
I want to specify that target can either be a Single? or a Double? only.
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Aug 11, 2011
in Delphi I have:
type osVer = (
osVerUnknown,
osVerWin95,
[code]....
I need to translate to VB...
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May 25, 2011
NOTE: I am mixing VB and C# - snippets come from different librariesI have a VB class definition as follows:
Public Class Session(Of TConnectionBuilder As {DbConnectionStringBuilder, New}, _
TConnection As {DbConnection, New}, _
TDataReader As {DbDataReader})
[code].....
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Apr 21, 2010
i have a simple code just have a look End Class
[Code]...
When i add num1 and num2 as above, compiler gave error that -- Operator + is not defined for types "type" and "type".How to define the meaning of '+' or any other operator in such situations?
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Dec 8, 2011
I define 3 arrays: ID(n), Hour(n), Showed(n). If Hour(i) = actual time, I get the data pointed by ID(i), if not Showed(i).
BUT... I can add new hours or modify some existent, but I need to have the Hour array sorted. If I sort this array, the ID and Showed will point to different data.
So I though some different solutions:
1 - To make a string array with all inside (a 7 characters ID, a 5 characters Hour and 1 char for showed (T or F)). It could work, but, how can I sort the middle part of the array (Hour)? So, this don't work.
2 - A 3 dimensions "multitype" matrix (1 dimension of type Integer, the second of type Date and the third of type Boolean). I have no idea about how this can be done.
3 - A 3 dimensions string matrix, some like the "all inside" array: ID converted to a fixed size string, hour converted to a 5 chars string (hh:mm) and Showed converted to T or F. And sort the second dimension.
4 - Sell my copy of Visual Studio and drive a taxi cab
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May 14, 2009
I have no idea as to how I can define a variable as "GLOBAL" in VB Express 2008. I used VB V 3.0 and if I remember correctly the statement "Global varName as Integer" allowed me to use the variable across different forms. I've tried the statement "Public varName as Integer = 0" on Form1 but Form2 tells me the variable is not declared.
The statement (in Form1) "Form2.Label1.Text = CStr(varName)" displays the value on Form2 in Label1 but I cannot then use the value again in Form2, e.g. "Label2.Text = Label1.Text". How I can transfer a variable value from one form to another and manipulate that variable in the second form?
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May 18, 2010
[Code]...
I have remplace the keyarr definition by my SQL query: With the code above, I can print both keyarr in a console. What should I change in the _sqlReader.Read() function in order to get keyarr definition like the first code. I would like that keyarr could be
interpreted by the rest of my code.
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Sep 18, 2011
Im trying to grasp session varibles, i understand what they are etc but i would like to know how to define a type for each session variable.Iv written it like this
Session("Title") = txtTitleContent.Text
How can i tell it what type of value is going to be in it, because at the moment im only playing about with strings, but what if i have an integer and want to pass it back to the back end to save it will throw an error saying "conversion from string to integer is not valid" should i use Cint to deal with this?
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May 6, 2010
I want to define a variable that is a collection of interfaces - it could be any interface that is defined for use in my app.
e.g. Dim x as New List(Of InterfaceBase)
Is there a base type for all interfaces that I can use for InterfaceBase?
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May 3, 2012
Is it possible to define a datagrid and chart name as variable? I'm planning to put the result into the predefined datagridview inside FOR and NEXT loop. I've been trying but getting different sorts of errors..
For i = 1 to 10
[Code]...
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Mar 9, 2009
public partial class _Default : System.Web.UI.Page
{
private bool isEditMode = false;
protected void Button1_Click(object sender, EventArgs e)
[code]....
What is the VB code equivalent for the above C# code. Mainly how to define Property (IsInEditMode) and Global variable (isEditMode) in ASP.NET?
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Aug 18, 2009
I'm converted a VB6 project to vb.net using the convert tool.Now i have a few declares that included passing variables as "as any" which vb.net doesn't like and it seems you have to declare them as there correct type so i have the following,So i suppose , Long and Long
Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory"(ByRef Destination As Any, ByRef Source As Any, ByVal Length As Integer)
and
Long again?
Private Declare Function CallNextHookEx Lib "user32" (ByVal hHook As Integer, ByVal nCode As Integer, ByVal wParam As Integer, ByRef lParam As Any) As Integer
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Sep 3, 2009
I am having some trouble with an array full of data which I am trying to process. The data has been picked out of an Excel spreadsheet and contains items such as phone numbers. The problem is that when I drop this array back into a spreadsheet, Excel being clever, decides that some of the phone numbers are numbers and removes the "+" from the front.[code]...
I know that adding a ' in front of the + will remedy this. What I need to do is find out which of the numbers in the array are actually numbers and which have spaces/characters in them. IS there a quick way of doing this without having to search through each individual character of each array position?
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May 10, 2010
I'm trying to make an application to do mathematical equations, but I also want to implement error checking. So that if someone doesn't put anything in one of the fields the output textbox will say "Error".
But the problem is that I already declared the variables I used as a numeric value, in my case decimal.
So, when I make an if statement that says if inputbox1="" then outputbox1="Error" it doesn't work.
I think that in order to get this to work I would have to have it setup so that the variable that is exported to the text property of outputbox1 could switch between being declared as a decimal or string value based on what the user put into the textboxes. But I'm not sure how to go about this. Declaring the variables inside the if/elseif statements won't work because the variables need to be declared before they are calculated within my if/elseif statements.
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Aug 8, 2009
I'm trying to wrap up a program I wrote in VB.NET and quick. I have a device that I am connected to through a serial port (COM4). It sent me 1056 binary bytes which I have stored in an array called newRecievedData. (see code below)
********** Start Code*********
Dim numberOfBytesToRead As Integer
numberOfBytesToRead = myComPort.BytesToRead
Dim newRecievedData(numberOfBytesToRead - 1) As Byte
[Code].....
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Mar 9, 2010
Is there any difference between the 2 methods below for calculating c ... specifically boxing/unboxing issues?
Dim a As Integer? = 10
Dim b As Integer? = Nothing
Dim c As Integer
' Method 1
[code]....
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Jun 2, 2011
The company I work for has an application where various users can log in and add their own "clients". Currently, via sql mail a confirmation email goes out to the client who has been added but the "From" value is generic i.e.Admin@CompanyA.com. What we need is a way for an email message to be sent to the new client but have the "From" email be that of the user adding the new client. When a user registers to use our system they supply basic info including their email, so when they log in and then add a client we would like to have an email sent to that client but have the "From" address be that of the logged in user instead of the generic one from our company. The email would have to be sent from our company's server but we want the sendee to be able to directly "reply" to the sender's email.
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Feb 1, 2011
I am working on a project where my class has to execute VB code provided by the user, to make it simple I am trying to recreate my own eval function, I am using the following code I found on the web to do this task.
Imports Microsoft.VisualBasic
Imports System
Imports System.Text
Imports System.CodeDom.Compiler
Imports System.Reflection
[Code] .....
The problem with code is that it can't access any variables or there values, so I have decided to get the variable names, there values types and there types dynamically and recreate them in the class that is being created dynamically. Any way to get the variable names there types and values in the current class or method, so that I can recreate them, and execute the user passed code, the user knows what variables are in the current class or method and there datatypes but he don't know there values as they may have changed, so he can't initialize them. Is there a way to do this, this code will be called in an asp.net page on page_load event, the code passed by the user is stored in the variable vbCode that is passed as a parameter.
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Apr 20, 2011
Why define a variable "As Long"? And how does it differ from "As Variant"?
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Oct 6, 2011
I get the error
Handles clause requires a WithEvents variable defined in the containing type or one of its base types.
in the following code..
Public Sub selCurrentManuf_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) _
Handles selCurrentManuf.SelectedIndexChanged
End Sub
The drop list to go with it is the following...
<asp:DropDownList
OnSelectedIndexChanged="selCurrentManuf_SelectedIndexChanged"
selectedvalue='<%#Container.DataItem("c1_manufidcurrent")%>'
[code]....
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Aug 23, 2009
I created a lable to handle DateTime = Now, It works fine. but when I moved it inside a FormView I Get the following Message. Handles clause requires a WithEvents variable defined in the containing type or one of its base types?
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Oct 19, 2010
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Click, Open.Click,Name.Click
SelectVid.ShowDialog()
End Sub
[code]....
I keep getting this error:
Error1'.' expected.
Error2Handles clause requires a WithEvents variable defined in the containing type or one of its base types.
Error 2 is also error 3
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Dec 8, 2011
I am auto generating data grid and I am using check box in Data grid View,Now i am invoking check box state changed event but it produces the following error Handles clause requires a With Events variable defined in the containing type or one of its base types.
Here the code
Private Sub PRNT_CheckedChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles PRNT.CheckedChanged
Some Stuff.
End Sub
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Mar 25, 2010
I am in the processing of moving an app from VB to C# but some of the classes I will just be moving to VB dlls to access from the main C# app. In doing this I am trying to get the VB dlls to utilize the main C# class lib. In this C# lib I have an abstract clase called base process, it sets up a background worker and handles all the progress tracking, errors, and even reports an ETA. To use this in a derived class in C# you would just do this...
public class SomeLongProcess : Common.Multithreading.BaseProcess
{
public void start()
[code]....
The problem is that if I do the equivelant in VB I get an error "Handles clause requires a WithEvents variable defined in the containing type of one of its base types". Well I can't do a WithEvents in the base class because it is C# so..
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Aug 26, 2011
I am trying to follow this thread
[URL]
and I have it pretty close but have one error.
Quote:Handles clause requires a WithEvents variable defined in the containing type or one of its base types.
That error is on both of these, in blue
Private Sub SpellChecker1_DeletedWord(ByVal sender As Object, ByVal e As NetSpell.SpellChecker.SpellingEventArgs) Handles SpellChecker1.DeletedWord
'save existing selecting
[code]....
I have added the reference, I have also added them to the toolbox. My dictionary is all set. What did I miss?
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Nov 22, 2011
i am getting errors on last two event handlers. what did i do wrong?
Error - Handles clause requires a WithEvents variable defined in the containing type or one of its base types.D:Shipping ApplicationShipping ApplicationForm1.vb75136Shipping Application
Error - 'PrintDocument1' is not declared. It may be inaccessible due to its protection level.D:Shipping ApplicationShipping ApplicationForm1.vb1119Shipping Application
[code]....
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May 11, 2009
Just upgraded a VS 2005 ASP.NET 2.0 website to VS 2008 ASP.NET 3.5. There was an error on the Sub Button_Click. It seemed to be a minor error, the website and the button worked just fine, as usual. What does the error mean?
Protected Sub btnDEreports_Click(ByVal
sender As
[code]...
Error 20 Handles clause requires a WithEvents variable defined in the containing type or one of its base types.
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Jan 27, 2011
So I have this:
Dim aBoolean As Boolean = True
Will it make any difference to just do this?
Dim aBoolean = True
In other languages, I believe it was a good practice to also define the type of variable it would be, for performance or something. I am not entirely sure with VB.NET.
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May 16, 2012
when i am selecting form the xaml file a button and then tap event from the right (in order to set the tap event) it auto generates this sub :
[Code]....
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