C#'s Equivalent To .Net's DirectCast?
Apr 21, 2010
Does C# have an equivalent to VB.Net's DirectCast?I am aware that it has () casts and the 'as' keyword, but those line up to CType and TryCast.To be clear, these keywords do the following;CType/() casts: If it is already the correct type, cast it, otherwise look for a type converter and invoke it. If no type converter is found, throw an InvalidCastException.
TryCast/"as" keyword: If it is the correct type, cast it, otherwise return null.DirectCast: If it is the correct type, cast it, otherwise throw an InvalidCastException.
EDIT: After I have spelled out the above, some people have still responded that () is equivalent, so I will expand further upon why this is not true.
DirectCast only allows for either Narrowing or Widening conversions on inheritance tree, it does not support conversions across different branches like () does.ie: C#, this compiles and runs:
//This code uses a type converter to go across an inheritance tree
double d = 10;
int i = (int)d;
[code]....
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Jan 14, 2012
i am using code to the value textbox2.text in the report and using the code like below [code]the textbox2 take various values in run time but when i run the code it display only the final value intermediated values are not displayed the whole situation is as follows.[code]
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Aug 4, 2011
I have a very simple problem where I have a MyList As List(Of MyBaseClass) but and a couple of MySub(ByVal Dummy As MyDerivedClassA)/MySub(ByVal Dummy As MyDerivedClassB). So I want to do the following ...
For Each MyInstance As MyBaseClass In MyList
MySub(DirectCast(MyInstance, MyInstance.GetType())
...
[code].....
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May 8, 2011
I learned how to use DirectCast over the last few days and it's really helped me. However, I have a similar issue, instead of textboxes I am looking at variables that are referenced in the class.To bring you all up to speed, I have four variables, a Boolean that dictates each of the 4 players I have playing my game. [code] I would assume it'd work similar to DirectCast but I am unsure. What I came up with caused errors: [code]
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Dec 1, 2009
I have 15 textboxes named MissionT1-15Is there a simple way to set all of their text to "Mission"?
missionT1.text="Mission"but for all of them with a loop?I saw something with directcast but wasn't able to make it work.
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Aug 28, 2010
Possible Duplicate: Why use TryCast instead of Directcast ? I want to know about the trycast and direct cast in vb.net. What is the difference between them?
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Feb 23, 2010
What is the difference between DirectCast and TryCast? Can someone illustrate it in very simple words along with an example?
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Jun 16, 2010
I am an experienced C/C++/C# programmer who has just gotten into VB.NET. I generally use CType (and CInt, CBool, CStr) for casts because it is less characters and was the first way of casting which I was exposed to, but I am aware of DirectCast and TryCast as well. Simply, are there any differences (effect of cast, performance, etc.) between DirectCast and CType? I understand the idea of TryCast.
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Jun 4, 2012
I have an SQL query that gets a max value so that I can decide the next value to use in an ID field. The code works fine when there's a matching result, but if the query returns Null, it throws a Specified Cast is Invalid error.This is the code I'm using:
LastID = DirectCast(SQLQuery.ExecuteScalar(), Integer)
What would be the proper way to check for a null value?
I suspect this is going to be one of those cases where within 2 minutes of posting myquestion, I finally hit upon the right combination of terms in Google to find what I'm looking for...
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Sep 4, 2009
I usually avoid VB's built-in conversion functions (CStr, CDate, CBool, CInt, etc.) unless I need to do an actual conversion. If I'm just casting, say from an object to a string, I normally use either DirectCast or TryCast, under the assumption that CStr, etc., are doing some extra stuff I don't need. But sometimes the DirectCast syntax is a little cumbersome, as in the following example.[code]SqlDataReader.Item returns an Object, which needs to be cast to a String. CStr is easier to read, type, and explain (IMO). My question is, does it matter which one I use? Should I just go with CStr (and CDate and CBool, etc.) and not worry about the extra work I assume those functions are doing? Is there any other downside to using these functions?
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Sep 21, 2010
I was wondering if there was anyway for me to get the string value of a point variable so that I can compare it. I tried to do something like:
DirectCast("point" & number, Point).ToString
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Dec 13, 2009
I turned option strict on, wich gave me some errors. The errors are quite easy to fix, but it seems like there are several ways of doing things. [code] 'previoustime' is declared as a TimeSpan, and the column "sluttid" is defined as a TimeSpan-column.Now, as far as I know, there are two ways of solving this; using CType and using DirectCast, like this: [code]
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Oct 13, 2009
Public Enum Fruit
Red_Apple = 1
Oranges
Ripe_Banana
End Enum
Private Sub InitCombosRegular()
[Code]...
Why does the Ctype work and the Directcast does not with the same syntax? Yet if I cast the selectedValue to an int before I DirectCast, then it works
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Oct 12, 2009
Does DirectCast, ctype, etc., are common function? Why it return type, and how do I used it? Is there others function where I need learn to be dot net expert?
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Aug 19, 2010
I find this behavior of TryCast in .NET 4.0 / VS 2010 rather confusing. In my understanding TryCast works like DirectCast, but will return Nothing instead of throwing an exception if a cast is not possible. VS 2010 / .NET 4
[Code]...
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Apr 24, 2010
Ever since I moved from VB6 to VB.NET somewhere in 2005, I've been using CType to do casting from one data type to another. I do this because it is simply faster to type, used to exist in VB6 and I do not know why I have to be using DirectCast if there is apparently no difference between them.I use TryCast once in a while because I understand that sometimes casting can fail. I however cannot get the difference between CType and DirectCast.
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Jan 14, 2011
in terms of performance (speed), does directcast beat ctype?
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Jan 16, 2009
I'm helping a colleague develop a "catch all" type error handler for some controls his application. What he wants to do is pass the object that has the error, and the type of that object, such a TextBox or ComboBox, and then call the DirectCast method within his handler to properly address the Text attribute within it. In general, the method is looking like this:
Protected Sub SpecialErrorHandler(ByVal TargetControl As Object, ByVal ControlType As String)
MessageBox.Show("Bad Juice: " & DirectCast(TargetControl, ControlType(ObjType)).Text)
End Sub
So far any attempts to do a type conversion within the DirectCast method (since it is expecting an object in the general signature) or to even pass in the a Type object properly set is not working.
Any ideas here, or is this one of those "Casting doesn't work that way." type scenarios?
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Jun 21, 2009
how can i cast a control to a type variable? heres the code i'm trying to use:
vb
Public Class form2Ex
Inherits Form2
Private list As Control = MyBase.CheckedListBox1
Private listType As Type
[Code]...
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Oct 15, 2009
How come this is not a valid DirectCast:
Public Sub FB(OF T0 As IGH_Goo, T1 As IGH_Goo) _
(ByVal A As DataTree(Of T0), _
ByVal B As DataTree(Of T1))
Dim val_A As T1 = DirectCast(A.FirstItem, T1)
End Sub
[Code]...
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Nov 30, 2011
why i get the error "DirectCast(err, SetupApiError) = InWow64 {-536870347}" when running the code below? i get this error when it calls the SetupDiCallClassInstaller method on the line: Case SetupApiError.NoAssociatedClass To SetupApiError.OnlyValidateViaAuthenticode Throw New Win32Exception("SetupAPI error: " & DirectCast(err, SetupApiError).ToString)
Dim result As Boolean = SetupDiSetClassInstallParams(handle, diData, params, Marshal.SizeOf(params))
If result = False Then Throw New Win32Exception
result = SetupDiCallClassInstaller(DiFunction.PropertyChange, handle, diData)
[code]....
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Oct 14, 2010
I know that AndAlso is equivalent to && and OrElse is equivalent to ||. But what is the cleanest way to achieve the equivalent of Visual Basic's And and Or in C#?For example, consider the following VB.NET code.The ValidateForControl method performs some validation and returns whether the state of the specified control is valid. The entire input form is valid if all controls are valid. However, each control must be individually validated even if one is invalid (which requires the operator not to short-circuit). Visual Basic's And operator is perfect for this situation, but unfortunately there's no equivalent operator in C# as far as I know (&& short-circuits).
[Code]...
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May 24, 2012
I am Validating a TextBox on it's KeyPress Event in VB.
VB.Net
If InStr("0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz`~!@#$%^&*()_+|[]{};:<>/?,.'" & """" & Chr(8), Chr(KeyAscii)) = 0 Then KeyAscii = 0
What will be it's equivalent in C# ?
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May 18, 2012
Let me know how can i use this Err in c#.This is VB Code:
If Len(sPart1) <> PART1_LENGTH Then
Err.Raise(vbObjectError, , "Part 1 must be " & PART1_LENGTH)
[code]......
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Jul 14, 2011
What I am trying to do is to check if a value matches one of two numbers (and easily be able to add to the numbers to compare to). Rather than doing a longer-winded way such as: [Code] I have found that this only works when SectionID is 2 or PageID is 8. If SectionID is 3 or PageID is 12 then it doesn't work. Why is this and what can I do to try to get around the problem?
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Sep 1, 2010
what is the equivalent for OLE in .net
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Jan 20, 2011
I'm normally at home in C#, and I'm looking at a performance issue in some VB.Net code -- I want to be able to compare something to the default value for a type (kind like C#'s default keyword).
[Code]...
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Mar 20, 2012
I am relatively new to Visual Basic. When it comes to logging, in Java I use log4j for logging.What is the equivalent in Visual Basic and can you please guide me to a good tutorial?
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Jul 28, 2009
private bool txtRegExStringIsValid(string textToValidate)
{
Regex TheRegExpression;
string TheTextToValidate;
[code]....
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Jul 17, 2011
I've got a large codebase which I'd like to expose to plugin authors to allow them to use VB.Net Express to code plugins for a server app, which is not available to them. My problem is that even with obfuscation, I'd rather not distribute the complete app and/or dlls, as even with obfuscation peeling apart a .NET assembly and puzzling out code is relatively easy to do. I'm interested in this because the licensor I obtain the code from requires me to protect IP and assets and while distributing .NET apps opens up the app to disassembly, keeping the server app private and allowing users to utilize a skeleton dll to code against is a happy medium.
What I'm looking for is some way or a utility to go through my server app source code and create a codeless version of the app which only contains method and property signatures.The intent is to provide a stub .NET dll for them to add as a reference and code against as if they were directly interacting with the server, without actually providing the server code to them, compiled or not. I can of course do this by hand but there are over 90 classes and hundreds of thousands of lines of code I'd rather not spend a week hand tweaking. Also, this presents a problem whenever new methods or code are added to the project. Finally, two separate projects is an even worse scenario.Because people will post suggestions that have little or nothing to do with the question, here's a short, clear example. I want to turn this class:
Public Class MyServer
Public ReadOnly Property Name() As String
Get
Return "Whatever"
[code].....
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