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I have been searching here in the VB forum for some clarification which I was unable to get. So if I have missed something that has already been posted please point me in the proper direction.
I am upgrading some software from VB6 to VB2008. According to the free "Upgrading Microsoft Visual Baisc 6.0 to Microsoft Visual Basic .NET" book states in chapter 11 page 241 that for Left, Right, Trim, Mid, etc can return a NULL in the VB6 environment. However, in .Net this is not allowed for a string to contain a Null value. One of the suggestions the book and migration tool suggests is to use the "$" after the function. Example: Left$, Right$, you get the point.
My question to all you out there is should I be doing what the book suggests to add the "$" to these functions prior to running the migration wizard that comes in VB2008? Are null strings still not allowed in VB2008 or future .net frameworks? Or is adding the "$" a waste of time?
Can someone please give me some clarification if I am on the right path by updating these functions prior to the migration?
Thanks in advance!
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.NET strings can certainly be 'null' ('Nothing' in VB).
The point the author was making (checking my own copy of that book), is that the old VB6 functions accepted arguments that may be Nothing, while the ones with $ after it did not. After upgrading to VB.NET, the VB.NET versions of those functions will throw an exception if you pass Nothing to them. For this reason, he suggests to try to isolate the issues before upgrading. Either way, you'll have to go through this, but the more issues you can resolve before upgrading, the less overwhelming the upgrade will be. I did a number of upgrades for clients a few years ago and I can tell you that this is true (and the book you're using is excellent).
David Anton
Convert between VB, C#, C++, & Java
www.tangiblesoftwaresolutions.com
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IIRC In VB6, if a string is assigned Empty, it just reverts to a zero length string "". I am sure you cannot assign Nothing to a string.
Panic, Chaos, Destruction. My work here is done.
Drink. Get drunk. Fall over - P O'H
OK, I will win to day or my name isn't Ethel Crudacre! - DD Ethel Crudacre
I cannot live by bread alone. Bacon and ketchup are needed as well. - Trollslayer
Have a bit more patience with newbies. Of course some of them act dumb - they're often *students*, for heaven's sake - Terry Pratchett
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Thanks David. I appreciate that. This clarification helps me now how to navigate through all these string modification functions.
Thanks again.
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The $ were added to add some explicit typing. In VB6, almost all library functions use variants (object references) rather than an explicit type; even if the argument in question only ever accepts a string, the parameter was still declared without a type.
Adding the $ to the Left/Right/Mid functions forced their type to string, so they accept and return only a string. Apparently (I did not know this), the non-string versions accepted a Nothing value for the objects they were passed? This surprises me, as VB6 always raised an error when nothing was passed.
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How to Call Stored Procedure from SQL 2005 to VB.Net 2008
Hafiz Mudasir Hussain
Software Engineer
Pakistan
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You call it the same way you would execute a plain old SQL statement: with a SqlCommand or a SqlDataAdapter. For instance, if you had a stored procedure called ListUsersByRole which took a single parameter, you might do something like this to retrieve all admin users:
dim cmd as new SqlCommand(yourConnection, "exec ListUsersByRole 'admin'")
dim dr as DbDataReader = cmd.ExecuteReader()
while dr.Next()
Console.WriteLine(dr("username"))
end while
dr.Close()
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1. Assuming you only want to know about the rows affected
using cn as new sqlconnection("ConnectionStringHERE")
dim cmd as new sqlcommand
cmd.connection = cn
cmd.commandType = StoredProc
cmd.commandText = "MyStoredProc"
dim Results as integer = cmd.executenonQuery
end using
I would also look up SQLParameters and SQLDataAdapters
Lobster Thermidor aux crevettes with a Mornay sauce, served in a Provençale manner with shallots and aubergines, garnished with truffle pate, brandy and a fried egg on top and Spam - Monty Python Spam Sketch
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I have a windows form application (VB) that can serialize and deserialize some JSON for me, however, I cannot seem to serialize and deserialize JSON in a console application (the ultimate goal here). I am starting to get the feeling that I am attempting to do something that is not even possible, even though I have seen a couple examples of this being done in C++.
Dim url As String = "<URL>"
Dim myHttpWebRequest As HttpWebRequest = CType(WebRequest.Create(url), HttpWebRequest)
myHttpWebRequest.Credentials = New NetworkCredential("user", "pass")
myHttpWebRequest.PreAuthenticate = True
Dim myHttpWebResponse As HttpWebResponse = CType(myHttpWebRequest.GetResponse(), HttpWebResponse)
Dim receiveStream As Stream = myHttpWebResponse.GetResponseStream()
Dim reader4 As New StreamReader(receiveStream)
Dim response3FromServer As String = reader4.ReadToEnd()
Console.WriteLine("responseFromServer: " & response3FromServer)
The above will retrieve the JSON and display it, no problem.
Dim deserializedOrder2 As New CardItems()
Dim ms2 As New MemoryStream(Encoding.UTF8.GetBytes(response3FromServer))
Dim ser2 As New DataContractJsonSerializer(deserializedOrder2.GetType())
deserializedOrder2 = TryCast(ser2.ReadObject(ms2), CardItems)
CardID = deserializedOrder2.CardID
Console.WriteLine(CardID)
Now obviously I have CardItems all set up with members, CardID being one of them, but I can't seem to get the value. Is there a problem with the above?
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Hi,
I have an application in VB6. connecting DB2 database using Neon client DSN connection. I am trying to add new record into a table.
I have a TDBGrid in a form which is connected to the rs ADODB.Recordset.
When i try to add new record into the TDBGrid and Save it. It gives me the an error "-2147467259 Insufficient Base Table Information for Updating and Refreshing" .
I have three Database region. Only in qaulity region it is working fine. Apart from this, It is giving the error for INT,TEST,Production region. However i am using same code for all region.
Could you please suggest me Why it is giving the error.
Befor posting this Messsage i took googled help but still problem isthere.
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I wonder what you Googled for, I got this[^].
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How can i save msflexgrid table in microsoft acess database?????
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In what language? The MsFlexgrid was part of VB6.
There's quite some stuff on Google on the subject. What have you tried so far?
Bastard Programmer from Hell 
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Lol Really i didn't know.... 
I thought that better learning is in forum rather than searching in Google
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No problem 
Forums are for asking questions, not for learning. Google is for basic research. The idea is that you do some research on your project, and ask a specific question when you get stuck.
Bastard Programmer from Hell
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Hello everyone
Does anyone know how can i insert information from combobox to listview???
in the form i have a combobox.this cbo has all the names of users.
with the pushing of a button i aim to put this name in lisview and so with all the names
Can anyone of you know how can i do it?
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Well, it would all depend on when you are going to insert the item. Personally, I would give the user a button to press when they want to insert a selected user. Then you could just do this:-
ListView1.Items.Add(ComboBox1.SelectedItem)
in the click event handler.
Hope this helps
When I was a coder, we worked on algorithms. Today, we memorize APIs for countless libraries — those libraries have the algorithms - Eric Allman
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Unfortunately No
The problem is that in Listview are 4 Cols
So nr (the first one)
Name (where combobox will place the data)
Thanks in advance
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I think you should explain more clearly how you want the end result.
When I was a coder, we worked on algorithms. Today, we memorize APIs for countless libraries — those libraries have the algorithms - Eric Allman
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in the form i have a combobox and 2 textboxes and 2 command buttons cmd 1 (insert) cmd 2 (Delete)
under them is placed one listview
Now,i have configured in loading form and everytime that forms load in the combobox are displayed some names
when you select one name and click insert,this name displayed on listview.after this you can add another name to the field and so on.
the name that you insert is displayed in col2 because col1 is dedicated to ordinal numbers (depending on how rows are in lisview.)
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Then try something like this:-
Dim lvi As ListViewItem = New ListViewItem()
lvi.SubItems.Add(ComboBox1.SelectedItem)
ListView1.Items.Add(lvi)
That will give you the users name in the second column.
When I was a coder, we worked on algorithms. Today, we memorize APIs for countless libraries — those libraries have the algorithms - Eric Allman
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Still the same problem.seems that doesn't work
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Well, I suggest you use the link provided by MicroVirus to learn the basics of the ListView. Then you should be able to work it out yourself.
When I was a coder, we worked on algorithms. Today, we memorize APIs for countless libraries — those libraries have the algorithms - Eric Allman
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What you do is you add a ListViewItem via ListView.Items.Add, and store the returned ListViewItem object. Then, you can use this object to add subitems via ListViewItem.SubItems.Add.
See, for instance, MSDN ListView sample[^]
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Maybe it's better to use ms flexgrid.but i don't know how to save flexgrid in my ms acess database.
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