In an application I am working on I have created a product class which represents an inventory item. I have also created an inventory class which represents a collection of product objects. In the constructor of the Inventory class I load 4 products into a product collection. Each product consists of a code, description price and quantity.
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I'm trying to loop through a collection object in vb2010.The code was originally used in Vb6 The book said that I needed to code a NewEnumerator method first in order to be able to loop through my collection. I coded the following:
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It gives an error for IUnknown, staging that IUnknown is not accessible in this context because it is a 'Friend'.In the line in the function I removed the Set since it's no longer needed.The error message for this line is '_NewEnum' is not a member of 'Microsoft.VisualBasic.Collection'What are these messages and how do I fix this in VB 2010?m_colCourse is not a system collection.
I have a simple Dictionary(of String, Object) that I need to iterate through and change items depending on some conditions.As I can't modify a collection that I'm iterating through, how do I achieve this?For example, the following obviously causes an Invalid Operation Exception:
Dim mOptions As New Dictionary(of String, Object)
mOptions.Add("optA", "A")
mOptions.Add("optB", "B")
mOptions.Add("optC", "C")
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Im trying to loop through a collection of controls see code:
Private Sub addZeros()
For Each ctrl As Control In Me.Controls
If TypeOf ctrl Is GroupBox Then
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I'm trying to just iterate through this xml and grab all of its data and add it to my collection(_personOC). Right now it's not working. How can I do this without having to specify the id? All I did was make a dataset with a person table and saved it as a xml.
Public Property personOC As ObservableCollection(Of Person)
Get
Return _personOC
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I decided to go back to the VB6 book, "Learn to Program Visual Basic Objects", so I can code it in VB2010. This has been a great learning experience. However I've run into a problem. I'm getting an error with a For....Each loop for a collection class. The error message states, Expression is of type 'China.Order', which is not a collection type." From what I've deduced the problem deals with an enumerator. I could be wrong.
View 2 Replieshow to loop through DGV selected rows collection?
View 2 RepliesI have a Collection, the keys are strings and the values are Collections. In the sub Collections the keys are strings and values are Singles/Floats. How would I loop through all of the data? I need to get the keys and values not just the values. I've tried this but it produces a cast error:
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CAUTION: Noob using Win32 API ahead
I want to display a list of open windows on my computer in a rich text box. So, I'm trying to store the names of all windows in myString, and then set RichTextBox1.Text = myString.
Here's the code
Imports System
Imports System.Collections.Generic
Imports System.Collections.ObjectModel
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I am trying to use a Web Service to return Json for a Collection of Users from a Database Table. I'm only new to .NET (< 1 week experience), and I don't want to use the UpdatePanel for AJAX. I have tried using the JavaScriptSerializer as well as Json.NET to serialize. Both cases seem to spawn an Infinite Loop.[code]
View 1 RepliesIs there a way to to combine line's 1 and 2? I only want to loop through a list of the selected items in this listbox. This works just fine, I just wondered if there was a collection of selected values returned that I could use to avoid having to do it this way.
For Loop1 = 0 To MyListBox.Items.Count - 1
If MyListBox.Items(Loop1).Selected = True Then
...
End
Next
I often use a for/next loop to cycle through a collection to find a particular member of that collection based on some criteria. This works fine in every case except one: when I want to then erase the very member of the collection I just found. For example, if I wanted to give the heave-ho to every obect in a collection class that has a member veriable Color equal to Red:
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The problem is once the collection class member is erased it makes to loop invalid because taking out the member reduces the total count of the collection in the middle of the loop. Eventually I get a "Index is out of range" error.This circumstance has bothered me every so often; I bet more experienced programmers have a different type of loop system that works better than this when you want to erase a collection member.
This is weird. I have a class that inherits from IEnumrable whose Count property is reporting 0 (zero) elements but the For Each loop steps into the loop body and tries to use the variable where it should just be moving on. My code:
On Error Resume Next
Dim d As Foo
For Each d In fooCollection
' use d and throws an exception
Next d
Weirder still, every time d is accessed i get an exception thrown in the output window:
A first chance exception of type 'System.NullReferenceException'
but i'm not stopping on the exception (not in a try/catch block).Is "On Error Resume Next" causing this weirdness?
Weirdness found:Per Rowland's and JohnH's comments i checked the Foo class:The GetEnumerator method inside of Foo didn't actually return anything! It had an empty body. That coupled with the On Error Resume Next before the loop caused the havoc! Wow this was ugly.
I would like to be able to save to a db and send task to email or as text msg for instance nevermind that.. I have two variables of type ArrayList they are "_mList1" , "_mList2" and "_mList3"
_mList1 stores the list of Telephonenumbers , _mList2 stores the list of StaffIDs and _mList3 Some concatenated string.
theses variable lists will hold some data in runtime as explained and i would like to use them to populate a DB table again mentioned
tblTask (TaskID(PK), Action, StaffID(FK), AssignedBy, TelephoneContacted, NotesCotent)
tblStaff (StaffID(PK), FirstName, Surname, Telephone, Address etc..)
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I am trying to make a collection of controls that I can loop through. So I have this code in my form... Dim WizardFrameCollection As New Control.ControlCollection(Nothing)
I then try to add controls to the collection by I get a error "Object reference not set to an instance of an object." WizardFrameCollection.Add(Me.GroupBox1) I am not sure why I am getting this error. Groupbox1 is a groupbox that is on the form.
I am encountering an error when looping through datarows. I searched SO and tried the solutions, but no luck. Collection was modified; enumeration operation might not execute.
Dim dRow As DataRow
For Each dRow In dt.Rows
dt.Rows.Add(dRow("CustNum"), dRow("SalesRepName"), dRow("mgrid"), "=""" & dRow("midValue") & """", dRow("dba"), dRow("sysDate"), dRow("statusID"))
Next
The error occurs the first time the code hits "Next". What would be causing Collection was modified; enumeration operation might not execute.How can I resolve this error?
In VB.Net is every ObjectCollection Zero based except 'Collection' object itself ???
Like if you have an ObjectCollection like attachments for a mail for example, which has .Count in it, then i have seen it is Zero based
But in case of the 'Collection' object it is 1 based. 'ie dim cc as new Collection.
I am just confirming this because you can't keep checking for each collection of objects if it is zero based or 1 based, because if you use the For...Next loop, then do we have to think always if it is
For iItem=0 to ObjectCollection.Count-1
-OR-
For iItem=1 to ObjectCollection.Count
i have a user define object which i'm initializing with data from external datafiles.... the purpose of this object is to reduce the amount of disk/data access and processing required every time i need to add an instance of this object to a collection.so, whenever i add a copy of this object to a collection, i would simply reference the "base" object, and avoid having to process all the data and perform the conversion and so on...the issue is when i add the object
Collection.add(Base_Object, Key)
the collection ITEM is a Reference to the base object and not a copy.
I can't figure out how to determine the type of an object in a collection. I want to do a For Each ... Next loop over the items in the DropDownItems collection of a ToolStripMenuItem. For those items that are ToolStripMenuItems themselves I want to take some kind of action. (The collection can contain other types of items, such as ToolStripSeparators). So I need to say something like: If Typeof(item) = ToolStripMenuItem Then .
View 1 RepliesCurrently, I have a listbox lstInventory where I have loaded some database information from a .mdb file. I am able to add new records, and they all display correctly.
Yet, I can't seem to retrieve or access any of the listbox items. (Not trying to reaccess database in here, yet). I am hoping to "Edit" an existing database record by matching it to the lstInventory's selecteditem property. Unfortunately, I am not able to retrieve anything (tried traditional CType(lstInventory.selecteditem.ToString, String) approach, as well as a debug.write approach (which I can't seem to display, even with a Listener-which is another issue in itself).
Furthermore, when I check the listbox.items.count property, it prints out as a "0" [using a messagebox.show()]
I have tried searching multiple forums, but found lots of "database into listbox" threads, and the MSDN website hasn't helped me yet. Do I need to know the collection's name (what would it's name be based on ?)? Or am I not converting the object into a printable/countable quantity?
I have a class which extends HashSet(Of T).I am trying to evaluate some custom properties of this HashSet during execution and make decisions based on those values.
During debugging, I am pausing execution and adding a Watch on my instance of this HashSet.
The Watch only provides me with a view of the Count of the HashSet and the objects contained by the HashSet.How can I get the Watch to show me the other properties of the HashSet?
I know you are going to lough about this , but I guess I deserve it ...I am sure I am doing something wrong , but I can't find it out ...I have created a collection , lets sayMyCollectionI have also created a class , lets call itMyClass
View 2 Repliesi have a collection wherein i store an object for example i have a textbox Object which have a text value = "TEST" then i store this on the collection then i change the text Value to = "SAMPLE" then i notice that the value of the first Text Object the is also change to SAMPLE...
What am doing is an UNDO function wherein i store the object state in a collection..why does the value of the textbox object changes in a collection
I'd like to store a set of key/value pairs in the application settings of my ASP.NET web app, but I'm not finding a straightforward way to do that. For example, these two questions tell me that StringDictionary etc. won't serialize to XML and suggest that I'll have to roll my own implementation. But it seems like this should be easier to do; after all, web.config is XML and < applicationSettings> is essentially a collection of key/value pairs, so it feels like I'm missing something obvious. Given my specific case below, do I really have to roll my own serialization, or is there an easier workaround?
The web app in question is a basic contact form that sends email to different recipients based on the value of a parameter; e.g. [URL]...The goal is to be able add or remove recipients (or change their addresses) by editing the web.config file so that I don't have to recompile and can easily maintain different configurations in test and production environments. For example:
// I can use something like this for the sender address SmtpMsg.From = New MailAddress(My.Settings.EmailSender)
// And then just edit this part of web.config to use different addresses in different environments.
<setting name="EmailSender" serializeAs="String"> <value>webcontact@exampledomain.com</value>
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I am moving from VB to C#. I am trying to loop through a collection class which is a collection of data classes but I can't seem to get the actual values out of the data class properties(find the correct code to do so). I have a method that loops through the collection class(Contacts) and saves each record(Contact). I am using reflection because my method will not know if it is Contacts class or a Customer class and so forth. Here is my code in VB(watered down)
Public Function SaveCollection(ByVal objCollection as Object, ByVal TableName as string, ByVal spSave as string)
Dim objClass as Object
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The C# code keeps returning null. In my locals window I can see the proprties on the class on objClass and the value of the propery but I can seem to figure out how to access it through code. I used the DictionaryBase because that seems to closely match would I need to do. My data class(Contact) has a bunch or properties that match the field names in the database of the Contact Table. After I get the propInfo variable set I then set up my SQLParameter with the fieldname, datatype etc and then set the value to the propInfo.value.
I like the PHP way of doing things but, it seems I am stuck with using a Collection of Object's to store/retrieve the data I need. I have my Collection loaded with my Objects's and the code to iterate through the collection, my problem is I am unable to retrieve the "key" as it would be called in PHP (I believe in this case it is actually the name of the object).
Consider the following example:
Dim xDoc As XPathDocument = New XPathDocument(fName)
Dim xNav As XPathNavigator = xDoc.CreateNavigator()
Dim sender As XPathNodeIterator
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As you can see, I am navigating an XML document, and creating an Object with some Key/Value pairs. The Object would look something like this if it were in JSON:
{"name":"John Smith","address1":"123 Anywhere St.","city":"This City","state":"FL"}
When I iterate though the Collection I can only get the value of the object, but I need the Key, in this instance I want "name","address1","city","state" to be stored in a variable for each iteration.
I have an object with a property that is a collection. When I point the PropertyGrid to the object it displays the ellipses for the collection. When I click it I get the generic collectioneditor. Of course the Add put fails because my collection is strongly typed. I need an example of how to create a collectioneditor that will create my collection's objects.
View 4 RepliesI am using LinqPad to learn Linq by querying the NetFlix OData source.Here is the query I got working which is awesome.[code].....
(Pardon all the comments...it is a testament to the fact I am experimenting and that I will change the query for various needs).There are two thing I cannot figure out.First.Let's say I only want to return the first 10 results.Second (and most importantly). I want to filter by a partial string of the genre.Each title contains a Genres collection. I want to show only Genres where the Name contains a certain string (like "Family").Even better filter using Titles where genre.name.contains "firstFilter" AND "secondFilter".Basically, I want to filter by genre(s) and I cannot figure out how to do it since Title contains its own Genres collection and I cannot figure out how to return only title that are in one or more genres of the collection.
Datatable object within class function + garbage collection?
View 3 RepliesBasically I have a simple while loop that loops through a datareader and saves the information into a object collection. Later on in the code I have a simple function that loops through the collection and exports the data to excel. The later part works flawlessly.OK the issue is that for some strange issue If I just let the while loop work as it should it misses records in the datareader stream. Now it sounds crazy but if i add a counter (x=x+1) along with a message box at the end of the loop to tell me the value of the counter (msgbox(x)) it ALWAYS saves the correct amount of records. If I take the msgbox line out it ALWAYS misses records. I am so boggled right now.[code].....
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