"IsNot Nothing" And "TryCast" Means In Code?
Jan 14, 2009Does anyone know what "IsNot Nothing" and "TryCast" means in code?
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What Exactly Does 'calling Code' Means
Dec 13, 2010What exactly does the "calling code" means? A method to do an action?or else.,
View 6 RepliesCode For "IsNot Nothing" In Linq-to-XML?
Apr 24, 2011I deal with a lot of XML for transformations. I typically find that I spend most of my time doing something like this[code]...
I suppose that is okay, but I'm just wondering if there is some better way of handling this where I Dim the element or attribute and then start processing for my transformation, if the element is not there it will just silently and gracefully fail and move on to the next thing in my code.
IsNot For String Comparison
Oct 12, 2010If Object.Value IsNot "Something" Then Can you do this, or are there certain cases in which it wouldn't work? Wasn't sure if this should only be used for integers and booleans.
View 3 Replies.net - Sort List Where Object IsNot Nothing?
Mar 2, 2011I am trying to sort a list of classes, and I need the classes with a subclass that isnot nothing first in the list. I thought the following would work but it doesnt.ListOfClasses.Sort(Function(x, y) If(x.SubClass IsNot Nothing, 1, 0)
View 3 RepliesVS 2005 ReadLine() While (inputRecord1 IsNot Nothing)?
Aug 22, 2009I am using this code bellow to read each line of a file doing stuff then repeat to the end in a while loop. My problem starts after that since I have to exit this loop then go back to it and start the process all over again 100+ times and I cant go back in since it knows I hit "Nothing" or EOF. Is there a way to do this without opening and closing the record 100+ times??
vb
inputRecord1 = inStreamReader1.ReadLine()
While (inputRecord1 IsNot Nothing)
Why Use TryCast Instead Of Directcast
Aug 28, 2010Possible 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?
View 2 RepliesDifference Between DirectCast And TryCast?
Feb 23, 2010What is the difference between DirectCast and TryCast? Can someone illustrate it in very simple words along with an example?
View 5 RepliesVS 2010 Isnot Requires Operands That Have Reference Types?
Mar 4, 2012First post here so Im sorry if im posting in the wrong place. Im trying to build a simple poker game which requires the program to recognise hands of each players. Luckily there are 3rd party solutions such as pokereval. However my problem comes when i try to convert a C# ported version of pokereval by Keith Rule, into vb.net. The following error shows up referring to the line with the *.
[Code]...
TryCast Fails Where DirectCast Works (.NET 4.0)
Aug 19, 2010I 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]...
.net - Casting DataTypes With DirectCast, CType, TryCast?
Apr 24, 2010Ever 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.
View 3 RepliesCan't Compare Types - TryCast(ans, T) <> Nothing Then ... Doesn't Work
Jan 30, 2012I want to see if try cast can convert user entered answer to the type I have specified. Here's what I have: Dim t as type = GetType(myType) Dim ans = console.readline() If TryCast(ans, t) <> Nothing Then ... 'Doesn't work` In the example above the intelisense doesn't even show t. How to make it work?
View 4 RepliesObject Casting - TryCast Statement And Base Class
Jun 17, 2009Here is a test program I wrote to explore a facet of object casting ...
Module Module1
Sub Main()
Dim class1 As MyBaseClass = New MyBaseClass()
Dim class2 As MyInheritedClass = New MyInheritedClass()
Dim class3 As MyBaseClass = Nothing
[Code] .....
The problem comes with the TryCast statement on class3. My intention is that class3 remains as a baseclass, but when the TryCast is applied, class3 morphs itself into an Inherited class which is not what I wanted. So is there a gap in my OOP/VB.NET knowledge and this action is legitimate or should class3 still be regarded as a base class?
Dim Array() As String Means And What Dim Array As String() Means?
Nov 20, 2010What Does : Dim Array() as String means and what Dim Array as String() Means?If I pass a array to function like below:Public Sub Array_AddSomething(ByVal strEntry As Object, ByRef strArray() As Object)
[Code]...
What Does () After Each One Of These Declaration Means Are They Arrays
Nov 19, 2009i am still new in VB.net if someon can just help with these codes below: [code] what does the () after each one of these declaration means are they arrays?!
View 2 RepliesWhat The First Line Of Each Property Means
May 5, 2009I have been given the following code that I want to change to VB however I dont understand the first line of every property:
1<ConfigurationProperty("mailSubject", DefaultValue:="Mail from TheBeerHouse: {0}")> _
2 Public Property MailSubject() As String
3Get
[code]...
Dataset.clear Method - What Does It Actually Means
May 13, 2009I think I've misused this method and would like to know what it actually does.I 've looked it up on msdn forum and found this
[code...]
What does it mean by removing all the rows in all tables? Is it the datagridview table? When it says "removing", does it mean that it deletes everything?
The reason I misused it is because I thought dataset.clear means it flushes the record held in dataset.
When I click on the add new icon on bindingnavigator, a new form will appear, which allows me to insert data
[code...]
when I close the insert form, the parent form will be activated and datagridview will display the new record I just inserted. I thought the dataset.clear method helped display the new added record but then I realised I could do without the dataset.clear method.
[code...]
Me.control.InvokeRequired Property Means?
Aug 25, 2009Me.datagridview.InvokeRequired property means in vb.netadil
View 3 RepliesVS 2010 Anybody Know What 'Long' Type Means?
Apr 11, 2011I saw something really strange today, that I have not seen before.I saw a variable declared as:Dim a as Long? I am obviously familiar with the Long datatype but what is Long?
View 4 RepliesDelete A Certain Row By Either Double Clicking It Or By Means Of Another Form?
Feb 21, 2010how do i delete a certain row by either double clicking it or by means of another form.
View 2 RepliesHow Does The Program Know That The Public Property X And Y Means The Coordinates Of The Object
Nov 9, 2011I've got a piece of code of a class. When initialised a new object is made on a picturebox. But what I don't know is how does the program know that the public property x and y means the coordinates of the object?
[code]...
Make A Facebook Application For Messages Purposes Means From That App?
Apr 30, 2011i want to make a facebook application for messages purposes means from that app i want to send and receive messages only?
View 11 RepliesTrigger Event Whenever Seconds On Stopwatch Change That Means Every Second?
Mar 6, 2009Is it possible to trigger event whenever seconds on stopwatch change (that means every second, but it has to be synchronized with seconds)?
View 6 RepliesVS 2005 E.Handled = True Means We Can Enter A To Z And A To Z In Textbox?
Nov 17, 2009Private Sub TextBox4_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox4.KeyPress
If (e.KeyChar < "A" OrElse e.KeyChar > "Z") Then
e.Handled = True
End If
End Sub
If e.Handled = True means we can enter a to z and A to Z in textbox.If e.Handled = False then what it means??
.net - Differences Between VB TryCast And C# "as" Operator When Using LINQ?
Aug 19, 2009I have a LINQ query to retrieve the maximum value of an integer column. The column is defined as NOT NULL in the database. However, when using the MAX aggregate function in SQL you will get a NULL result if no rows are returned by the query.Here is a sample LINQ query I am using against the Northwind database to demonstrate what I am doing.
var maxValue = (from p in nw.Products
where p.ProductID < 0
select p.ProductID as int?).Max();
C# correctly parses this query and maxValue has a type of int?. Furthermore, the SQL that is generated is perfect:
SELECT MAX([t0].[ProductID]) AS [value]
FROM [Products] AS [t0]
WHERE [t0].[ProductID] < @p0
The question is, how do I code this using VB.NET and get identical results? If I do a straight translation:
dim maxValue = (from p in Products
where p.ProductID < 0
select TryCast(p.ProductID, integer?)).Max()
I get a compile error. TryCast will only work with reference types, not value types. TryCast & "as" are slightly different in this respect. C# does a little extra work with boxing to handle value types. So, my next solution is to use CType instead of TryCast:
dim maxValue = (from p in Products
where p.ProductID > 0
select CType(p.ProductID, integer?)).Max()
This works, but it generates the following SQL:
SELECT MAX([t1].[value]) AS [value]
FROM (
SELECT [t0].[ProductID] AS [value], [t0].[ProductID]
[code]....
While this is correct, it is not very clean. Granted, in this particular case SQL Server would probably optimize the query it to be the same as the C# version, I can envisage situations where this might not be the case. Interestingly, in the C# version, if I use a normal cast (i.e. (int?)p.ProductID) instead of using the "as" operator I get the same SQL as the VB version. if there is a way to generate the optimal SQL in VB for this type of query?
Does Changing Generic List Capacity Means Copying Contents?
Mar 31, 2009If I increase the capacity of a given list, or add elements until count>capacity, does this mean the program is actually copying the entire list's contents to a new space in memory (similar to redim preserve with arrays)? If so, than I have really been hurting the performance of my lists, as before I was inserting and adding without a second thought. This seems a strong restriction on the dynamic abilities of lists.
View 2 RepliesWhat This Line Means - Inherits System.Windows.Forms.Form
Mar 20, 2009What this line means? Inherits System.Windows.Forms.Form
View 3 RepliesCNC Control Program, Based On A DLL - Acces All Functions By Means Of Softkeys ( F-Keys At Top Of Our Keyboards )
Apr 8, 2009I'm working on a CNC control program, based on a DLL that someone else wrote. No problems with that sofar, as i get good support from the writer.
The problem i do have to tackle is the following: I want to acces all the functions by means of softkeys ( the F-Keys at the top of our keyboards ) when the program starts it shows the Main menu softkeys ( F1-F12), and each F-key has a function assigned to it, some will make the machine move, others will show another menu, or a fileopen/save dialog, depending on the chosen keys.
All works fine and handy-dandy, except for the F10 key, it seems to be "Sticky", when i press it, the program will not react to any other key, only the F10 key can get it back in "normal state" accepting every key with a function assigned..
How to "unstick" the F10 after pressing it?.. because pressing F10 now, means no other key will do anything, and that may become dangerous, when the machine is moving and it must be stopped..
Where To Place Database In VB Project And How To Access With C:,D: Etc Means Open Location Not Fixed Location
May 3, 2010dim cn as oledbconnection
cn = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:valid.mdb")
[code]......
Modify Few Byte In A File Via A Stream Does That Means That Full File Is Rewritten?
Jun 9, 2010If i use a stream to modify few bytes in a file without changing the total number of bytes
does the stream rewrite all the file even if just few bytes have been replaced?