Length Checking In VBA With Null?
Jan 7, 2011
I have some code that is meant to check the length of the values in the text boxes, and if any of the boxes has no content the length of the string is 0 (or null). Here is the code:
If (Len(Form_MainScreen.Ctl48.Value) Or Len(Form_MainScreen.Ctl49.Value) Or _
Len(Form_MainScreen.Ctl50.Value) Or Len(Form_MainScreen.Ctl51.Value) Or _
[code]....
When one string is blank, the length check becomes "null" and so does the whole statement.But if the length checks are all not null, the if statement becomes a "1" and then procedes to execute the Do X procedure again.
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Dec 15, 2011
I have a fairly simple piece of code:
Private _PurchaseDelivery as PurchaseDelivery
Protected Overrides Sub InsertItem(ByVal index As Integer, ByVal item As PurchaseDeliveryItem)
[Code]....
Which is inside a class which overrides a custom list base. The code is occassionaly throwing an unhandled exception, System.NullReferenceException, on this line when used in production:
If _PurchaseDelivery IsNot Nothing AndAlso _PurchaseDelivery.DefaultSKUBinID.HasValue Then
DeafultSKUBinID is declared as an Integer? (Nullable Int) in the PurchaseDelivery class. I cannot see what might be causing this error, why would this be returning an error?
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Dec 3, 2011
I am working on a program that will take in a string of length 7 containing either R,G or B for the colours. The program will then check that the string if 7 in length and if it contains any other characters than R, G or B then it will be invalid. I created this code but when I enter the right string length and characters it always gives me the error for not having the right string length.
Private Sub get_cars()
Dim Letter As String
Dim valid As Boolean
Dim position As Integer
txtPosition.Text = position
[Code] ......
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Mar 14, 2011
This is related to my last question.Even though Access considers Nulls and zero-length strings (ZLS) separate values, often developers wish to treat them as equivalent for the sake of an If...Then statement or some other stretch of code. One way to accomplish this is to write code like this:
' Not so efficient
If IsNull(varAge) or varAge = "" Then
' do something
[code].....
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Jul 12, 2010
Currently, whenever I pass a string to the db, if that string is empty, then i set that object to NULL by doing the following:
IIf(DescriptionTxt.Text.length > 0, DescriptionTxt.Text, DBNull.Value)
I was thinking about writing a function to reduce the length of this code, and make it more consistent.However, I was wondering, is there already a way of doing this in .NET 3.5?
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Jun 11, 2011
[Code]...
By my logic, this should only assign .length to index IF the length of strItem is longer than 0. This check is there in case the listbox is empty, or the user has not selected an item. However, everytime I go through this code without an item selected I get:
[Code]...
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Feb 17, 2012
checking im my textbox contains null valuefor example i have ten textbox how do i know if a textbox has no text in it?then gotfocus to that specific textbox?
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Sep 6, 2011
I'm using Visual Basic .NET to work with a USB HID device.Most of the time, I can receive data from it perfectly... but one out of every thousand transfers or so, my code will think it has received data when it actually hasn't.The device writes to an array of bytes. I wanted to check to see if the received packet is empty, by doing something like this:
If myDevice.dataPacket(1) <> Nothing then
myDevice.rxDataReady = False
[code].....
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Nov 14, 2011
ve a simple vb code similar to the below,
Function getvalue (ByVal Val as double) As string
Dim Num as Integer
Dim Prd as double
[code].....
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Apr 11, 2012
Is there anyway to check for a null here before it reaches this part of the code? tmpLabelData(0) = m_node.Item("CONTAINER_NAME").InnerText. Some XML has it while others do not. I cant seem to find a nice way to handle a null on these?
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Nov 15, 2011
I'm querying a SQL DB and sometimes the result is Null, so I thought I would test this but my code results in an error "Data is Null. This method or property cannot be called on Null values."
Here is a snipet of my code:
For i = 5 To 6
cmd = New MySqlCommand(query2t & i, db)
rdr = cmd.ExecuteReader()
rdr.Read()
If Not IsDBNull(rdr.GetUInt32(0)) Then
[Code] ......
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Oct 25, 2011
I have an ASP.NET application that crashes when a null date value is returned.
The code line is:
excelWorksheet.Cells("A" & xlRowCounter).Value = IIf(IsDBNull(dRow("sysdate")), "", Format(dRow("sysdate"), "MM/dd/yyyy"))
Error message:
ERROR: System.ArgumentException: Argument 'Expression' is not a valid value.
How would I check for a null date, and replace it with "" in my app ?
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Oct 15, 2010
I keep getting the error "Object reference not set to an instance of an Object" on the below highlighted line of code and I understand why. It's because I'm checking for something that hasn't even been initialized yet. My question is, what's the best way to check a DataTables row count without getting that error before refilling it?
If Not ds.Tables("tblNotes").Rows(0).IsNull(0) Then
ds.Tables("tblNotes").Rows.Clear()
End If
adp.Fill(ds, "tblNotes")
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Mar 15, 2012
I'm working with a database application and i want to check if there is a null value in a specific column but it works only when its not null but if its null it throws an exception automatically. I tried to change the null value property of this column but I'm not able it shows a message that its not a valid property. I tried to change the source code in the code editor but it changes back automatically. Is there a way that I can work around this?
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Aug 24, 2010
I am trying to write a generic function that will check each database parameter to see if it is null, and if so, return DBNull; if not, return the object.So here is my function:
Public Shared Function CheckForNull(ByVal obj As Object) As Object
If obj <> Nothing Then Return obj Else Return DBNull.Value
End Function
[code].....
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Oct 16, 2011
I have a Javascript function for my select box, but after I included runat="server" to it, the script debugger highlights on this line below:
' for (i = 0; i < sourceTo.options.length; i++) { ' and says:
SCRIPT5007: Unable to get value of the property 'length': object is null or undefined
I included it because I wanted to loop through it in code behind and perform some other stuffs?
Code:
<select multiple size="8" style="width: 135px" runat="server" id="outletFromBox">
<option value="JP">Jurong Point</option>
<option value="IMM">IMM</option>
[code]...
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May 27, 2010
I constantly find myself having to do code similar to the following.[code]Is there anyway to check for both on a single line? When i'm checking a condition for a great number of answers, I sometimes end up with conditionals 6-sets deep. If i check for null first, an error still pops up, even though VB shouldn't check since the first condition failed. i.e.[code]
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Jun 25, 2009
how to check null excel worksheet?
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Apr 3, 2009
I have a DataGridView1 populated by sql searches. On the rare occasion that nothing is returned, my app cannot make use of data so I'm trying to check for null values. My code below is not correct because IsDBNull is not a member of the of the DataGridView1.
If DataGridView1.SelectedRows(0).IsDBNull Then
MsgBox("Nothing to display")
Exit Sub
End If
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Sep 7, 2009
I need to check if a value from a date column is equal to null. I can't find how to do it.
Wat I got now is:
if ds.tblBooking(row).CancelledOn.compareTo(dbnull.value) = true then
But this doesn't seem to work, I think it's because I'm using a strongly typed database.
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Feb 27, 2012
I'm implementing a State Machine in WF 4.0. In some transitions, I have added a condition where I check that some variables have the expected values. The variables are enums and booleans, and everything is fine.
However, now I tried to evaluate when a property is null. I have and argument in my workflow, let's say, 'MyArgument'. In a transition, I try to put a condition like 'MyArgument.MyProperty = Nothing'. I never developed in VB.NET, I don't know if I'm missing something here...
VS2010 gives the following error: "Error 4 Compiler error(s) encountered processing expression "MyArg.MyProp = Nothing".
Operator '=' is not defined for types 'XXXX' and 'XXXX'
The type names are exactly the same, and I have debugged VS2010 to ensure that my assembly is not loaded from 2 different locations.
How can I check if the property is null or not?
BTW, I'm using VS2010 SP 1, with .NET Platform Update 1 installed, on W7 64 bits.
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Feb 7, 2012
I am trying to implement a function for my SSRS report which will return a color value depending on the values of three dates.
[Code]...
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Jul 7, 2009
I am using following code in rowdatabound fn.
Protected Sub gvwMileStone_RowDataBound(ByVal sender As System.Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs)
[code]...
ddlEProjectLevels is dropdownlist in edititemtemplate.Whwn i click edit in 1st row ddlEProjectLevels gets loaded with data from database.But in 2nd row dropdownlist does not contain values.Again in 3rd it gets loaded from db.Means in alternate rows,when i click edit dropdownlist(ddlEProjectLevels) doesnot load values.Can anybody help?
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Apr 17, 2009
this is not working?
[Code]...
End WhileI am trying to read from the ": " to the end of the line. I keep getting this error: Index and length must refer to a location within the string. Parameter name: length
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Feb 17, 2011
am getting the above exception while swaping Items in the list(lstRoutePriority).PFB my code
if (lstRoutePriority.SelectedIndex > 0)
{
//Swap the two items
[Code].....
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Jan 6, 2010
I have a field displaying on a datagrid that the user has asked to be variable length based on the data that is returned. Is there an easy way to determine how many characters are returned for a field and then converting that to a pixel length so that I can change the length of the field in the code.
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Mar 23, 2009
"Index and length must refer to a location within the string. Parameter name: length" whenever I run this code
[Code]...
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Jul 21, 2010
If using the following in an if statement I get an error: If trg.Name.Substring(4, 6).ToUpper <> ("ABCDEF") Then I get the error: "Index and length must refer to a location within the string. Parameter name: length"
I assume this is because the string (trg.name) is too small for the 4, 6 substring. What would be the correct method of working around this problem? VB.net Studio 2008.
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Aug 4, 2010
Is there any better performance by checking for a true value like this:
[CODE]..............
Than like this:
[CODE]..............
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Jan 31, 2012
When I load in the file to my program.
GPRS: 232154,456464,546
IP Addr: 123.456.2.789,9001
Interval: 12.5422
It appear Length cannot be less than zero. Parameter name: length.
My program is...
Private Sub Loadbtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Loadbtn.Click
'Dim strFileName As String
[Code]....
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