Provide Cast Methods For Cast Operator Overloads In C#?

Jun 3, 2009

I read somewhere that older VB .net (pre VB .NET 2005?) couldn't use overloaded operators in a C# class. Is it true for overloaded cast operators?Either way do you guys think it's a disadvantage for a C# class library not to include them and arithmetic methods as actual methods for other languages, like:



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C# - Runtime InvalidCastException With Implicit Cast Operator?

Oct 13, 2009

I have a C# library that internal clients configure with VB.Net Their scripts are throwing an InvalidCastException where they really shouldn't.

So the code is something like this (massively simplified):

public class Foo {
public static implicit operator Foo ( Bar input )


Strange - it looks like the compiler can find the cast operator but it's lost at runtime. Surely the VB and C# IL will be pretty similar here?

The code is dynamically compiled - the compile happens the first time a user logs into the app. it's being compiled as VB.Net against .Net 3.5, and I'm not using any COM interop.

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.net - Why Have Equals Methods Have All Started Throwing Invalid Cast Exceptions

Mar 5, 2010

Several of my overriden Equals methods have started throwing Invalid Cast Exceptions -

Unable to cast object of type 'System.DBNull' to type Common.ResolveUser'.

This occurs when binding List (of T) (where T is of type ResolveUser in this case) to a combo.

Equals Method:

Public Overrides Function Equals(ByVal obj As Object) As Boolean
Dim i As ResolveUser = CType(obj, ResolveUser)
If i.UniqueResolveID = UniqueResolveID Then Return True


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Invalid Cast Exception Was Unhandled - Unable To Cast Object Of Type 'System.String' To Type 'System.Windows.Forms.TextBox'

Feb 9, 2012

Sub cmdExit_Click(ByVal
sender As System.Object,
ByVal e


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Are Generic Operator Overloads Allowed In .NET 4

Dec 15, 2010

I am assuming "No", but I cannot find conclusive proof on Google to back this assumption. Using keywords of ' "generic operator overload"' yields exactly 1 result, and removing 'overload' gives more, but no direct statement to the issue.

My thinking is given an abstract class, it'd be great to be able to implement a generic operator overload that a derived class can use in such a case when said operator overload has to return a New copy of the derived class, yet the code for each overload is the same. If that makes any sense.

This touches back to my previous questions on my custom Enum class and overloading the bitwise operators (And, Or, Not, & Xor), but, this particular thought was prompted by a mere curiosity of "Can it be done?".

Here's what one of my custom enums basically look like:
The parent, EBase is nothing special, just hosting common Name and Value properties, plus two shared operators, op_Equality and op_Inequality.

Friend NotInheritable Class EExample
Inherits EBase
Private Sub New()


Then (in theory anyways), calling EExample.OneA Or EExample.FiveE would work because the compiler would know to call the generic operator overload from EBase, know that EExample.Enums matches the IEnums interface constraint, and automatically supply T.

That or I'm just swimming up a certain creek here without a paddle and over-analyzing things. But it's an interesting thought, no? What is StackOverflow's consensus? Do I need to lay off the Spice a little bit?

PS: I use /* */ style comments because Markdown doesn't handle VB-style properly.

PPS: I know that, in the last example, Return New T( ... ) is invalid, but I can't think of a proper syntax that would articulate the basic idea.

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Provide Db Scalar Methods In All Classes?

Mar 5, 2009

We build a class (i.e. Server) and create a LOAD method that loads a dataset with all the details of that object.We need all that information sometimes... but what about when we only need one piece of data from that object (i.e. webserviceUrl).Should we build classes with a bunch of scalar methods that get back single pieces of data as opposed to only getting ALL the data and then only taking what we need?It's a waste to get all the data when we dont always need all of it but it also will take longer to write the extra methods..

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Why Framework Provide Event Hanslder And Overriable Methods For Action On Controls

Aug 2, 2009

What does the framework provide the eventHandler and equivilient Overriable method for most of the events on controls?


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InvalidCastException - Specified Cast Is Not Value

Apr 9, 2010

I have a field named 'UserID' in my OLE database with the type 'Autonumber'. But when I try to cast it to a variable of type 'String' I get an an InvalidCastException - Specified cast is not value.

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Specified Cast Is Not Valid

Sep 25, 2009

I was debating on placing this in the Office Automation section, but I think that the error is actually unrelated to concepts in Office Automation, and instead related to VB.Net.

Anyways, I have been programming a Metrics application for the past few months. For all intensive purposes, I have just completed the programming. However, I recently started to get the error "Specified cast is not valid". You can see the stack trace below:


Message: Specified cast is not valid.
StackTrace: at Microsoft.Office.Interop.PowerPoint.OLEFormat.get_ Object() at Metrics_Application.Utilities.PrepareGraph(Present ation mainPres, String ObjectNum, Int32 slideDiff) in C:RSNF MetricsMetrics ApplicationMetrics


I am passing into the method the Powerpoint Presentation object, the string specifying the Object name of the graph Ole Shape, and an integer for the slideDiff (to help differentiate which slide the method is modifying). Also, for context, I am using this to automate a PPT presentation, using Powerpoint.Interop COM objects.

I have tried to research this on various forums. Typically, it seems like this problem is found when accessing databases, or when someone tries to put a string into an integer variable (or another type of incompatible variable type). Looking at the code, I always bring in the string for the Object the variable type is correct there.

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Specified Cast Is Not Valid?

Nov 16, 2009

frm = New ItemInventory("", Me.cbFabric1.Text, Me.cbColor1.Text)frm.ShowDialog(Me)after this in the openned form's Form Load event i'm doing the following

Dim dv As DataView
'here i've executed stored procedure
adapter = New SqlDataAdapter(cmd)


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Specified Cast Not Valid

Dec 15, 2011

I am having a problem with a datareader.


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'specified Cast Is Not Valid' Error

Jun 21, 2010

I'm trying to make simple payroll system using 2003 and Access 2007. When I press 'delete' button in this application, having a "Specified cast is not valid" error.

Dim strSQL As String
strSQL = "select*from EMT where Empno='" & mskEmpno.ClipText & "'"
comEMT.CommandText = strSQL


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.net - Cast String To TimeSpan?

Dec 9, 2009

I tried to parse string to TimeSpan like the following :

Dim dt As DateTime = DateTime.Now
Dim timeCheckin As String = Format(dt, "HH:MM:FF")
ts = TimeSpan.Parse(timeCheckin)

It threw error like this:

System.OverflowException: The TimeSpan could not be parsed because at least one of the hours, minutes, or seconds components is outside its valid range.

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.net - Linq To SQL Cast Exception?

Sep 9, 2010

I am trying to Delete an entity but am having trouble with an InvalidCastException. The debugger breaks at the Next statement in the ForEach loop.My entity class is called Material.

Dim materialsTable As Table(Of Material) _
= (New DataContext("Server=.SQLEXPRESS; Database=Materials; Trusted_Connection=yes;") _
.GetTable(Of Material)())


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.net - LINQ To SQL Invalid Cast?

Sep 3, 2010

I'm getting an invalid cast exception but I'm not sure why, here is the list of my conversions.

char(4) -> String
varchar(50) -> String
tinyint -> Integer
char(1) -> Char
bit -> boolean


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.net - Specific Cast Not Valid?

Apr 12, 2011

Dear friends I face a strange problem I use Linq-to-SQL to insert data in When I insert data into SQL Server through a DataGridView it gives error of which column data type is "integer" but when I insert data through textbox it not give any error

So I face problem of datatype "integer" to error of specific cast not valid

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Cast A Date From A Format To Another

Dec 28, 2009

I was having trouble with casting this date from one format to another, i will be glad if i can get some pointers how to fix it. i have the following date:


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Cast A Double To An Integer?

Aug 30, 2010

I would like to cast a double to an integer, but rather than keep the numerical value the same I want to keep the bit pattern the same (this is for a compression algorithm), is this already possible in, or would I need to try and come up with my own method for doing this?

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Cast An Object Into Its Type?

Mar 1, 2012

I have a method which receives an object as parameter. This object is always of a class I have created, it will never be something simple as string, integer, etc

In my simple example I have created a class called ClassThatWillBeUpdated that requires a type for some reason not shown in the example

Public Class ClassThatWillBeUpdated(Of T)
Private _count As Integer = 0
Public Property Count() As Integer


Or maybe it would be possible to call the DoWork(of T)(item) directly when creating the thread, but as far as I know it's not possible to make a thread run a method that has (of T) as that is basically what I'm looking for

Needless to say, the above code would fail during compile as I have no idea how to do it, if it's even possible. I'm using .net framework 3.5

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Cast Float To Integer In ASP.NET?

Nov 3, 2011

I am trying to assign a specific width to my image in (using So I used the next code:

<asp:Image ID="PercentageImage" runat="server" Height="7px"
Width='<%# Eval("votsGraph") %>'
ImageUrl="~/images/bar.JPG" />

So how do i cast this one? (The type of votsGraph is float.)

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Cast String To Name Of A Web Label?

Dec 8, 2010

HI, using vs2008 and building a web app. On a asp page called blackjack.aspx, I have four labels with id of lbBJTStatusP1 lbBJTStatusP2 lbBJTStatusP3 lbBJTStatusP4.

I want to address those labels in a single sub by casting the casting two strings into the control name, so that string lbBJTStatusP & "1" would refer to lbBJTStatusP1.This is done on the code behind page.

So far I have tried this but with no success. boxct refers to either "1" "2" "3" or "4".[code]...

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Cast String To TimeSpan?

Aug 23, 2010

I tried to parse string to TimeSpan like the following :

Dim dt As DateTime = DateTime.Now
Dim timeCheckin As String = Format(dt, "HH:MM:FF")
ts = TimeSpan.Parse(timeCheckin

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DataTable Cannot Be Cast To MyTable Unless DataTable Was First Cast From MyTable

Nov 3, 2010

I have a class that inherits DataTable, because we needed a couple of extra properties and methods.I did not create a derived DataSet to hold them because you can add myTable to a dataset because myTable is ultimately, a DataTable after all.My issue comes when I've used ReadXml or adapter.Fill or some other method to fill a DataSet.So when I attempt to set myTable = DataSet.Tables(0), I get the InvalidCast Exception or whatever it is.I know that DataTable cannot be cast to myTable unless the DataTable was first cast from myTable.So I feel that by some combination of nested Casts it could be done.I want to override the Copy method of the DataTable or the Widening and Narrowing operators or even all of the above. Some one please tell me it can be done.Now, I do have something that works for now, but it just feels sloppy to me and I know there HAS to be a better way.[code]

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Invalid Cast Exception?

Feb 16, 2011

see from the following function why I would be getting an "Invalid Cast Exception"? More specifically this is the error "Conversion from string "yyyyMMdd" to type 'Integer' is not valid." I am trying to convert a DateTime value from the database to a String with the format "yyyyMMdd" so for example October 22, 1985 would be "19851022".dbReader(fieldName).ToString("yyyyMMdd")Here is the entire function ...

Private Function GetDBReaderDateValue(ByVal dbReader As IDataReader, ByVal fieldName As String) As String
If dbReader(fieldName) Is DBNull.Value Then


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Invalid Cast Expression?

May 29, 2012

How do I get rid of invalid cast expression from the Values in the Combobox to fit in the equation in examgrade? I tried to resolve it by looking it up on MSDN, and the like but couldnt figure it out.I tried using Examgrade = ().ToString but that did not work.FYI this is my first real program, I successfully made this once in C# but deleted the source files, so this is Visual Basic and a hell of a lot easier to get this far.The asterisks mark the problem line

Public Class Calculator
Dim quarter3 As Integer
Dim quarter4 As Integer[code].....

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Linq Specified Cast Is Not Valid?

Mar 10, 2011

I created a master record in the master table and then a record in the detail table. when creating the detail record i get a Specified cast is not valid error. Now another weird thing is that once I create the master record I can't query and verify it was created. But when i got to sql management studio I can see the master record. Below is my two procedures and the table definitions.

Implements System.ComponentModel.INotifyPropertyChanging, System.ComponentModel.INotifyPropertyChanged
Private Shared emptyChangingEventArgs As PropertyChangingEventArgs = New


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Mvc - MOQ: Can't Cast Moq.Mock To Interface In .Net

Nov 3, 2010

i am writing a simple unit test to check if the proper view name is being returned by an ActionResult in VB.Net MVC 1. The controller requires a service and I am trying to Mock the service but keep getting this error.Unable to cast object of type 'Moq.Mock`1[SRE.Web.Mvc.INotificationService]' to type 'SRE.Web.Mvc.INotificationService'.As I said, the simple and im not sure where to go from here.

<Test()> _
Public Sub Index_Properly_Validates_Email_Address()
Dim fakeNotifcationService As New Mock(Of INotificationService)(MockBehavior.Strict)


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Specific Cast Is Not Valid

Jun 14, 2012

I am Working on Teghax Component.Using This Component we want to find out Block title attribute of dwg file or autocad file in a client server socket application.

1> We get Block title attributes properly of dwg file in windows application form using the Get_DwgFileAttribute function().

2> We also get Block title Attributes properly in that way:-We take a class library where we take a this class we use Get_DwgFileAttribute function().Then We access the particular class from another project

But when we use the same class(Keep same structure) in client server socket program.Then it gives an exception.i.e ,"Spaicfied cast is not valid"I am Not getting any reply form teghax developer..I attached exception screen sort. How to solve this Exception

Code given Below :


How to fix this Exception...........

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Unable To Cast Object

Mar 9, 2012

All I am trying to do is select one school id. Do you know where I went wrong? ty

Public Function findId(ByVal table_name As String, ByVal name As String)
con.ConnectionString = connection_String


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Unable To Cast Object?

Mar 24, 2011

unable to cast object of type dataset to type datatable.Dim dataTable As DataTable = DirectCast(dataGrid.DataSource, DataTable)

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