Handle Nothing Returned From Function?
Mar 18, 2009
When the AlertsSettings.xml is not present the Appsettings is assigned to nothing. The variables that follow that definition rely on the existance of that information which will normally be set by the load method. But when there is a problem and either of the variables do not get a value how do I handle that in the code that relies on those values. The Settings class deserializes an xml document and assigned values to properties.
Sub Main()
Dim Appsettings As Settings = Settings.Load("AlertsSettings.xml")
Dim AlertsServer As String
[Code].....
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Sep 7, 2010
I tend to use
If Not IsDBNull(dr("data")) Then
myData = dr("data")
End If
to catch nulls. Is there a better way? It seems I use this over and over again? Anyone write a function to check this something like
mydata = IfNotNull("data")
I don't know how to handle the different data types that could be returned.
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Apr 4, 2012
How to give another function's returned value in LINQ.[code]but in above query I should write code to store the return value of GetObjProperty Value(p) and add obj-p and returnValue combination to the dictionary.The last line below code is wrong. but please suggest me how to correct it. My intention is, I want output collection(say dictionary) of each fruitname and its color(returned by other function call) for all the fruits which the GetFruitColor is not nothing(it can be empty or valid string).[code]In above code last line is wrong. So how to put getFruitColor in k, how to correct it to save the k value and give me output as dictionary of fruit and k value.
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Sep 5, 2010
Why this code doesn't work? It returns an unexpected value actually total = 0.
total = Cscore(TextBox1.Text) * CDbl(TextBox2.Text)
When trying this
total = TextBox1.Text * TextBox2.Text
It returns the expected value but I need to pass textbox1.text to the function to get the desirable value
The function is this
Public Function Cscore(ByVal score As Integer) As Double
Select Case score
Case score = 100
Return 5.0
Case score >= 95
[Code] .....
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Apr 2, 2011
I have many functions that perform mathematical calculations.
Here is one for example:
Public Function internaldiamofcasingpipecalculation(ByVal Externaldiameterofcarrierpipe As Double, ByVal insulationthickness As Double) As Double
[Code]....
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Feb 22, 2010
I'm new to VB.NET and want to parameterise the SQL Connection Strings in my VB.NET App. I've added a function to my Main Form to retrieve the App.config File like:
Imports System.Configuration
Imports System.Configuration.ConfigurationSettings
Public Class MainMenu [code]....
In my other forms when i want to reference the Connection String, i get an error saying getConnStr is not declared?
Private Sub UpdDept_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Try
myconnection = New SqlConnection(getConnStr()) <=============
Dim mycommand As New SqlCommand()
why i get this when i've declared the Function as Public?
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Aug 5, 2011
This should be a fairly common question, but I haven't found a straightforward answer anywhere.
If I instantiate an object within a function in VB.NET and return it, does it return it be reference or by value. IE - should I be worried about performance if I write something like this:
Public Function ret_obj_func() As big_object
Dim ret_obj As New big_obj(<lots of stuff>)
Return ret_obj
End Function
If I call this function from somewhere else, will it instantiate the object in the ret_obj and then create a deep copy to pass back a copy to the caller, Or will it just pass back a reference?
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May 2, 2012
I'm trying to establish a connection to my SqlDatabase while getting the connection string from a function. This will eventually lead to dealing with the appconfig file, but for now I'm just getting the basics established.
Imports System.Data.SqlClient
Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
[code]....
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Jul 2, 2009
Combobox with bound rowsource, but I want to change the displaymember to a string returned by a procedure. In Access/VBA I would have a little function to build the string, then simply code the recordsource of the cbo as:
"SELECT ClientIDS, fnGetName([ClientIDS]) AS ClientName FROM tblPerson ORDER BY fnGetName([ClientIDS])".
Pretty straightforward, but I've messed around with this for hours in VS2005/VB to no avail.SELECT ClientIDS, fnGetName
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Feb 25, 2009
I have a 2 dimensional array of groupboxes that I use to populate a form setup so the first indice is a tab number and the second is the groupbox number.The user can dynamically add tabs to the tabcontrol but I need to add and populate groupboxes to the new tabpage and I can use existing groupbox data in the array for default values.I understand I have to code a deep clone of the source groupbox as it has textboxes in it so I want to add a cloneGBox function that returns a new, populated groupbox when I pass in the x,y indices for the source groupbox in my array.
dim gbx as groupbox = cloneGBox(x,y)
and code cloneGBX as
public function cloneGBox (byval x as integer, byval y as integer) as groupbox
[code].....
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Jul 16, 2009
I am calling an Oracle function PKGDummy.F_EMPDATA using vb.net.
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Jul 27, 2010
I have the code below. The code returns a string in (IntersectingPoints) for X and Y. I need X and Y values to be in single and stored in an array to deal with later.[code]...
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Jun 1, 2012
Have seen some solutions for C# but do not know how to solve the issue in VB.NET.
Query:
Dim Query = (From t In myEntities.Bookings
Where(t.Ref = Someid)
Select t.People).Sum()
t.Ref field is an Int and so is t.People.
The SomeId value is the primary key of the related table. This issue is that there will not always be records in the Bookings table with a Ref value of Someid - so the query throws the following error.
I have seen others have got around this problem with catching the error, but from reading up on this and as per the error information it seems there should be a solution (in VB.NET) to cast the query or some of the fields in the query to nullable types?
Error is as follows:
The cast to value type 'Int32' failed because the materialized value is null. Either the result type's generic parameter or the query must use a nullable type.
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Jan 25, 2010
I have the following statement, I want to turn it into a Public Shared Function :
If isEmployee Then
Dim employeeInstance As New Employee
employeeInstance = GetEmployeeInstanceByUserId(userId)
[Code]....
Public Shared Function GetWorkerInstance(Byval isEmployee as Boolean) As ...(not sure what to write here)...
There two possible return Type. I'm not sure what I should declare for the function return type.
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Aug 5, 2011
If I instantiate an object within a function in VB.NET and return it, does it return it be reference or by value. IE - should I be worried about performance if I write something like this:
Public Function ret_obj_func() As big_object
Dim ret_obj As New big_obj(<lots of stuff>)
Return ret_obj
End Function
If I call this function from somewhere else, will it instantiate the object in the ret_obj and then create a deep copy to pass back a copy to the caller, Or will it just pass back a reference?
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Jul 14, 2009
I have a Class MessageIndex which holds an integer. I have a custom DataGridViewComboBoxCell which has a MessageIndex variable. If the MessageIndex is not set, the cell acts as a normal DataGridViewComboBoxCell; if the MessageIndex is set, then the GetValue and SetValue methods of the DataGridViewComboBoxCell are overridden so as to return the value of the object from its DataSource at the index of the integer stored in the MessageIndex.
As far as I can tell from stepping through the code, that actually works fine. The object returned by the GetValue function is fetched from the DataSource, based on the integer stored in the MessageIndex.
The problem is that when the DataGridView is displayed, all of the cells are blank. The values of the cells can then be set using the ComboBox dropdown, which appears to work fine.
But why are the initial selections not being displayed? As I say, as far as I can tell, the correct information is being retrieved by the GetValue function of the DataGridViewComboBoxCells when the form is initially displayed. It's just not ending up on the screen.
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Sep 27, 2010
When I declare two datatables and fill them both from a datatable returned by a function in class, that when i filter the one it seems to filter the other aswell?
For example:
I declare the datatable and initiate my class:
Dim DatatableOne As New Datatable
Dim DatatableTwo As New Datatable
Dim MyClass As New MyClass
I then call the function that returns a datatable and apply it to datatable1 and 2 Then fill two DataGrids with the table:
DatatableOne = MyClass.GetTable()
DatatableTwo = MyClass.GetTable()
DatatableOne.DefaultView.RowFilter = "Name = 'Tom'"
[CODE]...
For some reason i don't understand but both grids end up with the filtered data?
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Jun 28, 2009
I have two functions written in VB.NET:
1) The first function (call it GetValues()) returns values in a SQL database as a list via a stored proc. One of the fields is DateTimeSubmitted. All of this data is displayed on my webpage using a repeater control. It works fine.
2) The second function (call it NiceDate()) I created to change the DateTimeSubmitted to a nice date such as "one minute ago" or "yesterday".
My problem is I have no idea which is the best part of the process to do the conversion (at point of data extraction or in pageload etc.) or in fact how to do the conversion.
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Jan 3, 2012
I'm having trouble accessing a DLL function that uses a HANDLE as a return type.This is the signature of the function within the DLL:
HANDLE netagentsearch(int nPort, int *nError); I am able to access the function fine with C++.
typedef HANDLE (*funcnetagentsearch)(int nPort,int *nError);funcnetagentsearch Search;Search = (funcnetagentsearch)GetProcAddress(hGetProcIDDLL, "netagentsearch");HANDLE test = Search(7, &error);
I understand that vb.net doesn't have a HANDLE type, but as far as I knew, you could use IntPtr instead. This is the code in vb.net: <DllImport("netclient.dll", EntryPoint:="netagentsearch")> _Public Shared Function GetDeviceList(ByVal nPort As Integer, ByRef nError As Integer) As IntPtr End Function Dim test As IntPtr = WirelessLedCtrl.GetDeviceList(7, error) The error I receive when trying to run the VB.NET code is:
DLLImport_Wireless.WirelessLedCtrl::GetDeviceList' has unbalanced the stack. This is likely because the managed PInvoke signature does not match the unmanaged target signature. Check that the calling convention and parameters of the PInvoke signature match the target unmanaged signature.
Is there something I am doing wrong?I just solved a major problem that I've been working on for 4 months, so if I end up having to use C++,
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Feb 2, 2010
how can i handle things in messagebox in if else function
for example
MsgBox("Are you sure you want to exit?", MsgBoxStyle.OkCancel)
if==ok
exit sub
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Oct 6, 2011
I have a window that I need to activate and the window name does not work in AppActivate("WindowName") because this does not work with partial captions etc... and the window name will be different depending on user. That being said I am able to use "GetwindowhandlefromPartialCaption" to retrieve the # value of the window name or handle. Is there a way to convert this or extract the name from the handle ID to use with AppActivate?
[Code]...
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Oct 6, 2011
I have a window that I need to activate and the window name does not work in AppActivate("WindowName") because this does not work with partial captions etc... and the window name will be different depending on user. That being said I am able to use "GetwindowhandlefromPartialCaption" to retrieve the # value of the window name or handle. Is there a way to convert this or extract the name from the handle ID to use with AppActivate?
[code]...
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Aug 1, 2010
I'm using this for a single value to search for.
intPositionOfApartment = InStr(StrConv(pStringToParse, vbUpperCase), "APT") Is it possible to search for more then one value such as "APT", "UNIT" ?
If yes please show me an example of how it should be coded.
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Jul 28, 2009
I want my console application to be able to do one function I have when you click one option on the windows context menu, and another function when you click another option.
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Mar 23, 2009
I wrote an application to handle a joystick with directinput. It works fine if it uses the handle of the main window but it doesnt happen the same if the handle is the one of the component that contains the joystick's operation.
I mean:
main form handle: 15
component handle (which is inside the window and the joystick needs the focus of this component to work): 25
It always work if the handle i initilizate the device is the main form (15).How can i use only the handle of the component?
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Oct 12, 2011
I want to make an numerical integration method with takes in an analytic function and integrate it over a specific interval. For the numerical integration procedure I want to use some procedures in nr.com. The problem is that these are programmed in C++ and they uses functors to pass a function to the integration method. How can I do this in VB 2010?
I want to initialize the function (i.e. set a=1,b=0 for function y(x)=a*x+b) and then pass the function to the integration method. Then when the integration method call the function it only calls the function with one parameter (i.e. x since a,b is already set)
What is the best way to do this in VB2010?I want to make a general integration method where I can pass any single valued function and integration limits.
I have just started using VB, and from what I have found so far it seems like the tools you have is
- to us a delegate for the function
- to use a lambda expression for the function
- send a pointer/adressOf
- to create a function class/structure and submit this to the function
As for now I am most inclined to create a function-class. But I am not really sure how.F.ex. I make different classes for each "uniqe function" I want to integrate, but how can I pass them to the integration function when I need to specify the argument type in the integration-function-call?This seems like a basic problem which applies to many Math operations, so I think it would be very useful to clarify this.
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Apr 1, 2010
I'm trying to undersatnd the syntax of calling a funciton and it seem confusing when I'm using a web service in ASP.net. Maybe this question should be in an ASP forum, but it is a VB question. This simple web service allows you to type in your name and it response with an alert box with you name.
My question is, How can you call a function with 2 arguments when the function is only defined for one. I understand that the second argument is actually a method that handling the respons, but how can you interchange function arguments for methods and how do you know that there are methods for
Here's my call:
<script type="text/javascript">
function HelloWorld()
{
var yourName = $get('txtYourName').value;
[CODE]...
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Sep 24, 2010
How can i get the scope identity parameter in my vb code. I have this so far....
[Code]...
How can i retreive this ID, in the DetailsView1_ItemInserted?
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Nov 8, 2011
I know this topic is all over the place, but I am not doing an INSERT, UPDATE, DELETE. My statement is a plain and simple SELECT statement and so far has worked with 116 different items in my database until I got to one.
I have a search engine and am going through every single product in our database to add information to it. This is all done through the website, but when I search for ProductID 331 and click on it, it goes to the error page that says Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression.
It doesn't make any sense to me that the website would error with only this one product. This is the statement I am using. Does anyone know why 1 product would be causing this error?
WebService:
Public Class ProductSearch
Inherits System.Web.Services.WebService
<WebMethod()> _
[Code]....
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Apr 5, 2009
what i'm aiming at doing here is returning every file on my drive that hasn't been accessed in 90 days. The first listbox has all the directories and the second works off that to return all the files... [code]
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