Setting Nullable Integer To String Containing Nothing Yields 0
Dec 14, 2010
I've been pulling my hair out over some unexpected behavior from nullable integers.If I set an Integer to Nothing, it becomes Nothing as expected. If I set an Integer? to a String that is Nothing, it becomes 0! Of course I get this whether I explicitly cast the String to Integer? or not.[code] Previously I had my code up here so without the explicit conversion to Integer? and everyone seemed to be fixated on/confused by that. There were a lot of suggestions that Option Strict On would catch this type of thing. However, this is actually a quirk of the string-to-integer conversion rules which predate nullable types, but still impact them.
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Jun 28, 2010
I wonder if this is not possible dim mystring as string="1" dim myint As Nullable(Of Integer) myint=0 myint=mystring It crashes on the last line why is that? mystring is already integer (1) , i dont have to cast using cint, i thought. option strict off- if this cause the problem
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Dec 7, 2010
I am trying to understand why the two code samples behave differently. I always believed the If() function to mimic the If language feature. Or am I looking at a behavior of Nullable(Of Integer) that is causing this?
Sample #1:
If Not String.IsNullOrWhiteSpace(PC.SelectedValue) Then
Dim pcFilter1 As Integer? = CInt(PC.SelectedValue)
Else
[Code]....
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Dec 1, 2009
I would expect the following vb.net function to return a value of Nothing, but instead its returning a value of 0.
[Code]...
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Aug 24, 2011
dim val1 As Integer? = If(5 > 2, Nothing, 43)' val1 = 0 dim val1 As Integer? = If(5 > 2, Nothing, Nothing)' val1 = Nothing What gives? Is this a bug, or am I overlooking something?
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Apr 19, 2012
If you assign a value to a nullable integer via a ternary operator, it can't become null..While this question may seem like a duplicate of many, it is actually being asked for a specific reason.Take this code, for example: Dim n As Integer? = If(True, Nothing, 1) In that code, the ternary expression should be returning Nothing, but it's setting n to 0. If this were C#, I could say default(int?) and it would work perfectly. Now it looks like I am going to have to ditch the ternary and use a regular If block, but I really want to use the ternary. If Nothing were truly VB.NET's equivalent to C#'s default, how can you explain this behavior?
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May 12, 2012
I've tried these two blocks but it returns the same value. I do not describe more, I simply just show the code:
Dim f As Nullable(Of Integer)
If f = 1 Then
Console.WriteLine("Equal")
[Code]....
It works in C# correctly...
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May 27, 2009
Why does this give variable A the value of zero (instead of setting it to nothing)?Dim A as double? A=If(2<3, Nothing, 6)
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Jan 18, 2010
How can I create a nullable numeric optional parameter in VB.NET?
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Sep 19, 2011
I have a LINQ2Entity problem, I want to get the value, string, from a database, so I select FProducts.Serial_number, and to end the query, I do .ToDictionary. The problem is, it tells me that it doesn't have sufficient parameters, to convert ToDictionary. So I need something like select FProducts.Serial_number, Nothing). ToDictionary. Also FProducts.Serial_number, 0).ToDictionary doesn't work.
Sub GetStatistics(ByVal ProductNumbers As List(Of String), ByRef Passed As Integer, ByRef FailedProducts As List(Of String))
Passed = 0
FailedProducts = Nothing
[Code]...
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Apr 5, 2009
I'm trying to set an Integer value from my.settings.The values comes frpm a listbox, and then inserted to settings (set to specialized.StringCollection)The problem is when i'm trying to get the values and apply them to my function.Error code: Conversion from string "65 & 71" to type 'Integer' is not valid.To me it looks right, but maybe i'm missing something.
Code: Dim test2 As Integer Dim test As System.Windows.Forms.Keysm trigglist As New StringBuilderor Each item As String In
[code].....
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Jan 18, 2010
how to implement Nullable Parameter of type string in vb.net
Function:
sub savedetail(byval name as string, byval age as integer)
if name isnot nothing then
some work
end if
[code]....
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Jun 19, 2009
I have 3 similar functions, that only change based on numeric type:
<Extension()> _
Public Function ToNullableShort(ByVal str As String) As Short?
Dim intReturn As Short
[Code].....
I was trying to make a generic function out of this, but couldn't do it. How can I make a generic function that will take a specific T and make it a Nullable(of T)?
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Mar 17, 2010
So I'm building an application that is going to do a ton of code generation with both C# and VB output (depending on project settings). I've got a CodeTemplateEngine, with two derived classes VBTemplateEngine and CSharpTemplateEngine. This question regards creating the property signatures based on columns in a database table. Using the IDataReader's GetSchemaTable method I gather the CLR type of the column, such as "System.Int32", and whether it IsNullable. However, I'd like to keep the code simple, and instead of having a property that looks like:
[Code]...
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Sep 8, 2009
I have a bit of ported code. It was automatically converted from VB6 to VB.NET. Now when if finally compiles, it produces output files with some values replaced with literal #ERROR 448#.I will eventually find out what's the problem, but I just wonder, if anyone knows what does this error mean. VB's Write function is used.
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Jan 16, 2010
I've tried rewriting this code several times, it spits out the bytes correctly, but then when trying to read the array created from the memory stream, it's empty, what am I doing wrong?
Dim bytes() As Byte = System.Text.Encoding.ASCII.GetBytes("test this shit")
Dim bytesString As String = ""
Dim i As Integer = 0
i = 0
Dim byteStream As New System.IO.MemoryStream
[Code]...
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Jul 27, 2009
Im trying to figure out how to query a dataset when I select multiple values in a list box? I have the list box linked to the dataset and am using a button to search the values selected in the list box. I don't know what to do!
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Sep 1, 2010
how can i convert these datatypes: date to string and integer to string.Because it must be in a string datatype when I display it in a datetimepicker and textbox.
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Jul 24, 2009
I have a radio button control on a web form. The members of my ListItem collection are
assigned the following.
Text No
Value 0
Text Yes
Value 1
So what I need to do, is to readd a varchar value from my database and if the column value returned equals 'Yes' then I need to select the radio button that has the assigned value of 1. Otherwise if the value read from the database is 'No', then I need to select the radio button assigned a value of 0
So how can I set the value for my radio button? I experimented and could not figure it out. The 'Yes' or 'No' value is stored in my database in the field ds.Tables("employee").Rows(0).Item("answer")
So I tried something like this which is not correct:
RadioButtonList1.Items.FindByValue(ds.Tables("employee").Rows(0).Item("answer") = "Yes").Equals(True)
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Mar 11, 2010
I am currently working on a custom data type, and wanted to implement a = operator.
I data type is a nullable date that returns a string value if date was supplied.
I want to allow the variable to be set like this
Dim nd as New NullableDate nd = Today Does anyone know how this can be done, or can anyone point me in the right direction?
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Nov 28, 2009
Any thoughts on what might cause a thread error like this?Error:InvalidOperationException was unhandledCross-thread operation not valid: Control 'Form1' accessed from a thread other than the thread it was created on.
Relavent Code:
Private Sub SerialPort_DataReceived(ByVal sender As System.Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
[code].....
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Oct 10, 2011
How do I convert from a string to an integer? Here's what I tried:
Price = CInt(Int(txtPrice.Text))
I took out the Int and I still got an exception.
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Oct 8, 2010
I know this is a proper enum:
Private Enum Months
JANUARY = 1
FEBRUARY = 2
...
End Enum
However, I want to have an enum where the string will solely be integers.
Example:
Private Enum ColumnCounts
01 = 5
02 = 4
03 = 40[code].....
Essentially, I didn't want to put the f in there, just wanted to do 01. The way this will be called is:
Select Case (nRecordType)
Case "01"
...
Case "02"[code].....
Because I'm not making an instance of it and not calling a constructor, there's no way to autopopulate a Dictionary.And I don't want to convert to integer so I'm not going to do an array. That is just in case eventually the value gets above 99 and the next value would be A0.I'm trying to think of easy future changes to this and backwards compatability.If you need more explanations, let me know.
Edit 2:This is what I've done now and I think it should work:
Public Class Part
Private Shared columnCounts As Dictionary(Of String, Integer) = New Dictionary(Of String, Integer)
Public Shared Function ValidateColumns(ByRef lstFiels As List(Of String)) As Boolean[code]....
I can't verify that it's going to do what I want to, but it doesn't give me an error when I build it so I'm crossing my fingers.
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Apr 10, 2010
[code]This code wont work, it claims it cant be converted from a string to integer, i have tried CInt, but that doesnt work either.
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Nov 8, 2009
I get an InvalidCastException was unhandled on converting the .value to .text but I can't figure out how to convert it. Tried a few different ways but nothing seems to work. load a file from disk and have that be assigned to the trackbar.value?
Dim FileName = (App_Path() & "SettingsPingTimeout.txt")
If File.Exists(FileName) Then
lblPingTimeout.Text = "Ping Timeout: " &
[Code]....
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Feb 23, 2012
I would like to convert for example the string "98" to the integer 98. Also, is there a way to specify that the value contained in the string is in hexadecimal and that "98" gets converted to 152?
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Jun 21, 2010
How would I ask the user to input what type of engine they want and getting an output of $150
Console.WriteLine("Enter EngineChoice for your vehicle:")
Response = Console.ReadLine()
EngineChoice = Convert.ToString(Response)
[code].....
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Jun 5, 2011
If strCardNum.Length <> 5 Then
MessageBox.Show("Please enter a 5 numbers.", _
"Georgetown Credit", _
[code]....
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Mar 1, 2010
[URL].. and why it wont let me convert string to integer? i was following tutorial learning VB 2008 using 3.5 framework
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Jan 22, 2009
I have a textbox which the user will enter a number into. I then have a label control which will perform a maths operation and write out the resulting answer; atleast this is whant I want anyway however this is not happening.
The code I have so far is
Protected Sub btnWork_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnWork.Click
Dim Work As Integer
[Code].....
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