Let's says I have a class called Customer :-
Code:
Dim Cust as New Customer("Fred")
I also have a function in a seperate class :-
Code:
Shared Function Example(Example As Customer)
How do I refer to the class itself from within itself? For example :-
Code:
' from within the Customer class, call the Example function
AnotherClass.Example(Me??)
Public Class Form1
Public Contestant As New ContestantClass
Public HighScore1 As New ContestantClass
Public HighScore2 As New ContestantClass
Public HighScore3 As New ContestantClass
[Code] .....
The problem I'm having is the first time I take a value, it gets inserted in the right section. The second time I insert a value, it inserts it in the correct place AND updates the previous value I inserted with the new value. So apparently when I'm doing:
HighScore1 = Contestant
It's pointing contestant AT highscore1 rather than taking the name, company, and score from contestant and then storing it in highscore1. How I can pass that info by value rather than by reference?
The case is that I have two comboboxes (country and state) and a simple code to populate the state combobox accordingly depending on the selected country. Ok this is simple and easy, and this code is within the country combo change event.The case is that I have more than one pairs of those comboboxes and I wouldnt like to repeat all the populate code into every country combo change event.Actually I would like to have only one function and just call it passing as parameter a reference to the combobox I want to populate. Then I could use that reference into the function.
View 10 RepliesI know strings are immutable, so the minute you change a string reference's value .NET makes a brand new string on the heap. But what if you don't change the value of a string reference; rather, you simply pass it into a function ByVal -- does this operation copy the string value on the heap as well? My inclination is "no," but I'd like to confirm.
For example:
Public Function IsStringHello(ByVal test As String) As Boolean
Return (String.Compare(test, "Hello") = 0)
End Function
Calling program:
Dim myWord as String = "Blah"
Dim matchesHello as Boolean = IsStringHello(myWord)
I know passing myWord by value makes a copy of the reference to "Blah", but since I have not tried to change the string itself, would it make another copy of the string on the heap?
VB.NET is not letting me dance with both feet, or piss with both hands. I've got one foot and one arm tied behind my back at every turn. I want to use this statement in a function:
Return CType(Formatter.Deserialize(FS), DS)
Seems doable, right?
Function ReadFileStream(ByRef FS As FileStream, ByRef DS As Object)
Dim Formatter As New BinaryFormatter
FS.Position = 0
Return CType(Formatter.Deserialize(FS), DS)
End Function
Right? I mean, CType only accepts a class name as the second argument. I can't give it an instance of a class, or it croaks. Yet if I try to pass the class name as the argument to that function:
DataInfo = ReadFileStream(FileStream1, DataStruct)
VB.NET croaks on this, too, complaining that "'DataStruct' is a type and cannot be used as an expression.". It's used as an expression by CType just fine outside of the function. Does the VB.NET legislature provide a clause that allows for a 'Type' to be passed as an argument in a function? Writing all the supporting code ten million times to deserialize a file using CType ten million times in a large application will get very complicated and tricky very quickly. It should be handled by a routine so that any cases and adjustments that come up can be dealt with in one spot.
Base class has one field to hold numeric balance value. With 2 methods that accept arguments for adding and subtracting the new input calculating new balance. Sub class has four fields dates, transaction, memo and amount.I have a deposit form, and withdraw form. Each time one transaction is entered it creates an object with sub class fields, then adds to the account collection. My problem is not understanding how to call the deposit/withdraw method and pass the current transaction amount back to the base class to alculate the new balance. Does anyone have any links to information/tutorials on how to perform something like this? As you can see with my code I have tried various different approaches without any success.
[Code]...
I'm sure there are several ways of achieving my goal but I am after opinions on what you think is the best option. I'm writing a vb.net application which (amongst other thinks) interfaces with media players in the home. Because there are different types of media playersI'm trying to structure it so each type of media player has it's own class which interfaces to a management class which sits on top of all the different devices types.
The device classes are responsible for discovering the phsyical devices and returning that information up to the management class. A device class may be responsible for monitoring 1 or more physical devices so..
[Code]...
I seem to have problem with passing a collection/sorted list/ list of strings from one class to another.I am using property procedure to pass it, however nothing is sent to another class. There isn't any error messages either.[code]
View 3 Repliespassing a variable to a sub procedure by reference. Not sure I understand how it works. Here is the code.
Private Sub bntcompute_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles bntcompute.Click
Dim x, y As Double
getnumbers(x, y)
displaysum(x, y)
[code]....
Is the newly modified variable actually being Passed back? and If so where in the statement is it passed back. is it being passed back to the call getnumbers or is it passed back to the statement displaysum?
I'm still working on the code in this thread [URL] and as I mentioned in that thread, I thought that passing objects around between methods would probably be bad for performance (perhaps not really noticeably at first but maybe if I did it enough then it could have an impact).
1. When you pass a reference type to a method using ByVal then what is actually 'copied' ? I understand that ByVal copies the object into the local method that you are calling where as ByRef passes a reference to the actual object so you can work with the original object. So when you have a Reference type and you pass this ByVal then does copy the entire object or does it just copy a 'reference' to the object?
2. When working with an object that relates to a 'physical' item, such as a file on disk or a network stream between two connected machines, then what happens when you pass it around between methods (this might be irrelevant depending on the answer to the first question) ? I mean if I have a NetworkStream object that represents the data stream coming from a remote computer, if I then pass that ByVal into another method then does that mean I am still working with the same data stream or a copy of it or what?
my proble is the following: I have a class MyClass and another class Modifier, which has a method ModifyMyClass(ByRef mc as MyClass) that receives a MyClass instance as ByRef parameter to modify it. A smell of the code is:
[Code]...
I have a 'property management class' that contains several functions and properties. I have several other classes that use the 'management class' as a property to derive the value of several of its other properties.Is there a way for me to reference the outer class from the 'management class' functions without having to pass it as a parameter? I ask because several different classes can have this 'management class' as a property and am having a hard time typing the parameter.
View 7 RepliesI have a function that accepts a String by reference:Function Foo(ByRef input As String)
If I call it like this:
Foo(Nothing)
I want it to do something different than if I call it like this:Dim myString As String = Nothing Foo(myString) Is it possible to detect this difference in the way the method is called in VB .NET?All the logic is in the second overload, but I want to perform a different branch of logic if Nothing was passed into the function than if a variable containing Nothing was passed in.
I have a class in which some of the fields are also classes.I can put values in the "normal" properties, but in the others when o try to assign values it gives the: "Object reference not set to an instance of an object"But the code compiles fine.
dados_Defenicao = New ServiceReference1.draftClaimEntryDefinition
dados_Defenicao.arCode = "123"
dados_Defenicao.claimMarket.warrantyType = "w" - Here it gives the error
How can i fix this ?
I have a class in which some of the fields are also classes.
I can put values in the "normal" properties, but in the others when o try to assign values it gives the: "Object reference not set to an instance of an object"
But the code compiles fine.
dados_Defenicao = New ServiceReference1.draftClaimEntryDefinition
dados_Defenicao.arCode = "123"
dados_Defenicao.claimMarket.warrantyType = "w" - Here it gives the error
If we are within the derived class then ofcource we can use MyBase keyword to access base class's object reference . That's fine , how can we take that base class's object reference outside that derived class's definition.My following code will explain what i want . Actually that is giving error right now, but it is explaining my requirement .
Public Class Base
Public x As String
End Class
[code]....
Actually there is error in ReadOnly Property BaseReference's Getter . Error is "Error 1 'MyBase' must be followed by '.' and an identifier. " how can i get base class object reference in Main method ?
I have a Parent Class Called Fuselage that containsfour child classes called Forebody, CenterBody, AftBody, and CrossSection. CrossSection classcontains objects common to Forebody, CenterBody, and Aftbody (example: width). How do I access thewidth property in CrossSection from within the classForebody?
Public Class Fuselage
Dim Forebody As ClsSection
Dim Centerbody As ClsSection
[code].....
Is it really impossible to create an extension method in C# where the instance is passed as a reference?
Heres a sample VB.NET console app:
Imports System.Runtime.CompilerServices
Module Module1
[code].....
I have a List(Of AddlInfo) with AddlInfo being an object. I'm trying to pass addlInfoList by reference into a function of another class:
[Code]...
This works if I'm not passing the reference into another class, but when I try to do this, I get the following error: Overload resolution failed because no accessible 'Sort' can be called with these arguments:
[Code]...
I need to create a new instance of a class that needs a member of the calling class. But i can't pass a reference to the calling class through the constructor.The solution i am looking for is something like this:
Public Class ChildClass
Public Sub New(args)
_MyMember = GetMemberFromCallingClass()
[code]....
I want this to work without having to manually pass any references or variables from the calling class to the new instance of ChildClass.
I have a question concerning some homework. Here is my answer:
Dim intResult As Integer
intResult= Square(4)
lblResult.Text = CStr(intResult)
Now, if I understand functions correctly, this statement should pass the value 4 to:
Function Square( ByVal intValue As Integer ) As Integer
Return intValue^2
End Function
...and assign it's return value to "intResult".
Private Function Token() As String
Dim Length As Byte
Length = 10
Dim Chars As Char() = New Char() {"a"c, "b"c, "c"c, "d"c, "e"c, "f"c, _
[code]....
is the above bolded line a correct .. it s not working too and the above code is used to generate a random password for users which should be displayed on the text box?
I am having a problem figuring this out. The text that is bold is where the problem is.
Imports Microsoft.Win32
Console.WriteLine(WMILookup("Win32_Bios","SerialNu mber"))
Private Function WMILookup(ByVal WMIClass as String,ByVal WMIItem as String) As String
[Code].....
I have a .aspx webform, with code behind to handle data entered by user, most fields are in double.At business layer, at other class, let say there is a function: [code]I just wondering whether this is the correct way of writing it? And if I have more than 20 fields of double value, then I should declare additional 20 double value?
View 2 RepliesI have a function that search database based on the 2 textbox value. I have a difficulty to call the function and pass the text box value to the function. This is my function: So I get this error:
{"Object reference not set to an instance of an object."}
Function getname(ByVal SearchedName As String, ByVal SearchedFirstName As String) As String
Dim temp As New System.Data.SqlClient.SqlCommand
Dim temp2 = ""
Dim sSQL = " select SearchedName, SearchedFirstName from student where SearchedName =@SearchedName AND SearchedFirstName = @SearchedFirstName"
[Code] .....
I have function in my asp.net/vb application with following signature:Public Function ExtractText(node As XmlNode) As String..I want to call it/pass xmlnode. How to create an Xml node with value:<mynode Id="7743" Type="context" StartNode="4356" EndNode="1234"></mynode>
View 1 RepliesI am trying to call the method with the following declaration[code]...
The structs should both be twodimensional arrays with indexes of 4,4 and 5,4 respectively. The second one is an out parameter.
I wrote vba function in excel and I want to call this function in vb.net with parameter passing.
View 2 Repliespass an array to a function, like the code below shows
Private Sub SomeFunction(ByVal PassedArray() As String)
For i As Integer = 0 To PassedArray.Count - 1
Debug.WriteLine(PassedArray(i))
[code]....
But is there a way to pass a constant array to a function in VB .Net, for instance in PHP you could write
function SomeFunction($array)
{
for($i=0;$i<count($array);$i++)
{
[code]....
So to reiterate: Is there any way to pass a constant array directly to a function in VB .Net? Is there any benefit in doing so? I imagine a few bytes of memory could be spared.
PS.SomeFunction({"some", "array", "member"}) ' this obviously gives a syntax error
It looks like passing a list's enumerator to a function "byval" is quite different than passing it "byref". Essentially, regular "byval" passing will NOT change the caller's "enumerator.Current value", even if the function advances the enumerator. I was wondering if anyone knows why this is the case? Is an enumerator a primitive like an integer, without an object reference, and hence changes to it don't get reflected in the caller?This function is byval, and gets stuck in an infinite loop, spitting out "1" message boxes, because the enumerator's "current" never advances past 5.[code]The difference between the two functions is only whether the listFirstItem__ function accepts a byval or a byref enumerator.
View 2 Replies
