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:
So you know how PHP internal functions usually return a boolean FALSE when a function fails, or some other data type when the function succeeds? Is this possible in VB .Net?For instance, lets say this simple code here Public Function TrySomething(ByVal Param As String) \what would go here??
[Code]...
You see I want to return a BOOLEAN false when a function fails, and a string when the function works. I've looked everywhere, and when I search for "return multiple types" all i find is Tuple.
Lets say I click a button on a form that calls a function in a data access class. This function inserts a record into a table in a database. The function returns an integer value for the record id of the newly inserted record. Now lets say the insert failed (syntax error, timeout, whatever). I can return a zero to the calling routine to indicate the failure, but not the error message. So in general, what's the most appropriate way to handle getting information back to a calling routine when the return parameter data type doesn't allow it?
Just so it's known, this question is mostly academic, even though I tried to use the concept in a real-world solution. I realize the example is contrived, but I believe the concept is valid.I want to write some fluent code like this:
[code]...
I realize that I can't force an anonymous type into a specific type (like implementing an interface or some other class), and I don't want the overhead of defining a specific class just to match my desired fluent name with the actual method name. So I was able to make the code work like this:
copy(my_first_file).to.Invoke(my_second_file)So there is no IntelliSense or type awareness there, and I have to include the Invoke in order to have the method run. How can I get more type safety and exclude the Invoke method, under these constraints: Anonymous Type returned from Method No additional classes or interfaces Preferably, I do not want to pass in another parameter to the copy() method that tells what type to return, unless copy becomes a generic method (but I think that means defining another class/interface, which I don't want to do)
In my project (which I inherited from someone) there are a lot of functions like:
Public Function DoSomething(ByVal s As String) ' Do something to public properties End Function
And they are called like this:
DoSomething(s)
So the return value is ignored (which is object, as I see in the docs). Is it safe to change all these functions to Subs? Could I break something which isn't so obvious?
I know a little about using a user specified type IE IIf(Of ReturnType)(ByVal expression as Boolean, ByVal TruePart As ReturnType, ByVal FalsePart As ReturnType) As ReturnType...Which works, however I've been trying to get this to work, but can't..
Protected Function InverseSign(Of ReturnType)(ByVal value As Double) As ReturnType Dim result As String Select Case Math.Sign(value) Case -1: result = "+" & Math.Abs(value).ToString()
[code]....
Using try cast just gives me the error saying ReturnType has no class-constraints? whatever that means..But my goal here is to be able to return either a string or double.. However every method I've tried to convert my result string to the ReturnType doesn't work.I've also tried simply overloading the function, but I can't because they only differ by return type. So that didn't work either.
Currently I have written a function to deserialize XML as seen below.How do I change it so I don't have to replace the type every time I want to serialize another object type ? The current object type is cToolConfig. How do I make this function generic ?
Public Shared Function DeserializeFromXML(ByRef strFileNameAndPath As String) As XMLhandler.XMLserialization.cToolConfig Dim deserializer As New System.Xml.Serialization.XmlSerializer(GetType(cToolConfig)) Dim srEncodingReader As IO.StreamReader = New IO.StreamReader(strFileNameAndPath, System.Text.Encoding.UTF8) Dim ThisFacility As cToolConfig
if i got a function with a try cath block inside and the function should return an integer.how would i do it that the function can return me a the error message?public function test() as Integer
I was playing with vb 2008 express and i created a function with no return type. Basically what it does is i specify a table name and a column name and it returns the value within but it doesn't type it until it gets to the calling variables type. So i have on function that i can use across all my tables.
Eg: dim mydate as date = getvalue("tblSRs", "datelogged") msgbox (mydate) dim desc as String = getvalue("tblSRs", "description") msgbox(desc)
Both return the correct values. were you always able to leave the typecasting till the end and whats the major downfall?
I am working on a project where I have to import a DLL file into a VB project that was created a few years back. The DLL was created in C++, and looks like:
I am an intern at my job, and I haven't had to use this yet, so my understanding is extremely limited, along with my usage of VB (I'm a C++/C# guy). Here are a few questions:
1) Looking at Dllimport, it seems like the last part outside of the parameters is a return type. Example code from another site:
<DllImport("advapi32.dll")> _ Public Function GetUserName( _ ByVal lpBuffer As StringBuilder, _ ByRef nSize As Integer) As Boolean
Is "As Boolean" the return type? If so, I tried using "Sub" and it says "Keyword does not name a type." Hence why I looked into declare, because it seems I CAN return void/sub as a return type.
2) Trying to use the types "CoordinateTuple" and "Accuracy" give me problems, saying that they aren't defined. How do I get around this since I don't think I can really define them, and what about the fact that they're pointers?
But i am now trying to declare time however i keep getting an error because i cannot get the type correct. I tried the following but get the following error: "Conversion from type 'Timespan' to type 'integer' is not valid".
Dim DeliveryTime as DateTime Dim DeliveryTime as Integer
In my database the DeliveryTime type is set to Time(7) so i would assume there should be 'Time' which i could use to declare it, but there isnt. What is the correct type i should be using?
Here is my exact code. There error is Input string was not in correct format:
GraphDate4 = String.Empty DeliveryProducts = "{ name: 'DeliveryProducts', data: [" If DataReader4.HasRows Then
I have a generic Class I'm using to hold information loaded from a database.I have a method which takes a DataRow as an argument, uses the object's known column name and extracts the data from the DataRow, such that:Dim loadData As T = CType(myDataRow("myColumnName"), T))works as my default assignment in most cases.Unfortunately, due to some horrifying design constraints, some of my columns may be null, and may also be taken from enumerations.This means that when <T> is Nullable(Of SomeEnumeration) the above code does not work because I can't cast 0 directly to SomeEnumeration.Zero.Is there some way to check whether <T> is Nullable(Of [Enum])? Or some way to write a method which allows Integers to be cast to Nullable(Of [Enum])?I feel like I'm forgetting something that would allow me to write one of the other of these, but my weak google-fu is turning up nothing.
EDIT: Okay, thanks to dasblinkenlight's answer below, I can detect when this circumstance is occurring, but what I need to do now is to take a type <T> which I know is Nullable(Of SomeClass), get a type reference to SomeClass and then create a new object of type Nullable(Of SomeClass) and assign that to LoadData.My problem was that I had a lot of difficulty in finding any function which would accept baseType as an actual Type.Parse accepted baseType as a parameter, I knew baseType was an [Enum] type because of dasblinkenlight's code, so I was, in this instance, able to code a solution. It's a solution which is very specific to my problem (i.e., T is Nullable(of SomeEnumeration)), but it's a solution nonetheless.
Assuming Anonymous Types are tailored to be used with LINQ, I'd like to use them for simply and fast data aggregation without an explicit class definition, like in this snippet[code]....
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.
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] .....
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?
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
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?
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
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
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
I have two Parser classes that inherit from a base class, BaseParser. I want to use either class as a parameter in another Monitor class. The Parser classes, CS600 and TCH600, both have two properties, RawDataList and SummaryDataList. The CS600 class's RawDataList returns a List(of CS600Data); the TCH600 RawDataList returns a List(of TCH600Data). The SummaryDataList returns similar classes in each Parser class. CS600Data and TCH600Data derive from a base class, BaseData.BaseParser also has RawDataList (List(of BaseData)) and SummaryDataList (List(of BaseSummaryData))The Monitor class has a private field, _thisParser which can be either of the two concrete Parsers above. I want to be able to call and use RawDataList and SummaryDataList of _thisParser within Monitor class, but when I construct the concrete Parser classes, Visual Studio notes that the RawDataList property of CS600 cannot override the RawDataList property of the BaseParser because they differ in their return types.
I thought that since CS600Data derived from BaseData (but also adds some new properties of its own) that I could use CS600Data wherever I use BaseData. What am I misunderstanding? How can I correctly construct these classes?
Public MustInherit Class BaseParser Protected _rawDataList As List(Of RawGasData.BaseData) Public MustOverride ReadOnly Property RawDataList() As List(Of RawGasData.BaseData)
