Datetime - InvalidCastException When Parsing Dates In .NET?
Mar 3, 2010
I'm trying to Parse dates entered into a TextBox into a DateTime value but I keep getting an exception in the TryParseExact method. What I'm trying to do is: DateTime.TryParseExact(tbAddDate.Text.Trim, "yyMMdd", New CultureInfo("sv-SE"), DateTimeStyles.None, row.Date)
This throws an InvalidCastException with the message "Conversion from type 'DBNull' to type 'Date' is not valid." I realize what is happening is that it's trying to set row.Date to DBNull which is not a valid value for a DateTime. What I don't understand is why it's trying to do this, as the documentation states that it should be set to MinValue and not DBNull.
As a sidenote, I know that I can get around a lot of these problems by using a DateTimePicker but the customer feels that they are very clunky as it's not possible to enter the dates directly with the keyboard.
In my application i have to create an excel report of records. everyday at a specified time the report of records added from last 24 hrs has to be generated automatically. i am unable to compare the dates.
how to manipulate the dates to determine which date will be 30 days more then the datetime control I have on my form. i need to take the chosen date from the DateTime control, and determine what date it will be in 30 days. Eventually I will use this process to search through the database to print monthly reports.
I would like to be able to parse vb.net code files, so I can examine the collection of Subs, Functions (and their contents, including comments), private variables, etc. I can be open the actual source code files. So for example, if I have:
I'm creating a vb.net winforms application that will take in user given strings, parse them, and print out labels with variable information. The given string will be used in all the labels, but the variable part of the string will change with each label.
My question is: is it better to parse the strings one time, then store those values in arrays, or to parse the string each time a label is printed? Which will perform better? Which is better practice? What is the proper way to test something like this?
I'm using two datetimepicker controls to set the start and end dates for a range of dates I'm searching for.I want to make sure that the start date selected is not greater than the end date. This code works, but it runs the messagebox prompt twice for some reason. I've tried to ignore it from doing this, but it's not working. Can someone tell me what's wrong?
Private Sub dtpStart_ValueChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles dtpStart.ValueChanged
I'm trying to match a certain DateTime value with the current system DateTime. I have a timer and a label on a form. Timer interval is set to 1000. When the form loads, the timer starts ticking. As soon as the current DateTime matches the value of the variable, it shows a message in the label. When I'm writing the following code, the values don't match even if the current system DateTime is equal to the variable. Label1 isn't showing 'Times Matched':[code]The default format of 'Now' is the same as I have stored in dtmVar variable. So there's no question of format mismatch. Does that mean 'Now' is not actually a DateTime property? Provided, my O.S. is Windows Vista Ultimate and all date/time settings are set to default.
I'm trying to match a certain DateTime value with the current system DateTime. I have a timer and a label on a form. Timer interval is set to 1000. When the form loads, the timer starts ticking. As soon as the current DateTime matches the value of the variable, it shows a message in the label.
When I'm writing the following code, the values don't match even if the current system DateTime is equal to the variable. Label1 isn't showing 'Times Matched':
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick Dim dtmNow As DateTime
[Code]....
Why is it so? The default format of 'Now' is the same as I have stored in dtmVar variable. So there's no question of format mismatch. Does that mean 'Now' is not actually a DateTime property? Provided, my O.S. is Windows Vista Ultimate and all date/time settings are set to default.
datetime1 and datetime2now two fields are have data ( date )in table recordi want to update only datetime2 is an emptyi am using visual basic 2010 ( visual studio 2010
I have one more problem with MonthControl.And when I bold some dates the program doesn't show bold dates on month calendar.When I move on next or previous month and get back to currently month the program normal displays bold dates. What's the problem?
I try to compare Datetime.Now with a Datetime variable I set, using the Datetime.CompareTo() method. I use a timer to compare these every second and display the result, but as the current time approaches the time I set, the result changes from 1 to -1, but never 0, which means these two are never equal. I'm suspecting the Datetime structure contains milliseconds?
Assume the following program is started at 1:59:01 AM on 3/13/2011 in the United States. The first time Timer1 ticks what will be the value of the TimeSpan (ts)?
Public Class Form1 Private Sub Timer1_Tick(sender As System.Object, _ e As System.EventArgs) Handles Timer1.Tick
I'm trying to add the date and time of Today into a Sql-database-field that has the datetype datetime.
[Code]...
the msgbox gives me the following result: 29/01/2011 18:49:21 my sqlException gives me the following error: 102 - Incorrect syntax near '18'. Is it better that i set the datatype to char in my sql database? It's maybe a bit easier? When I do that, can I calculate with these date?
Dim CustID As String = txtSrchCustID.Text Dim FirstName As String = txtNewCustFName.Text Dim SecondName As String = txtNewCustSName.Text If CustID And FirstName And SecondName = "" Then MsgBox("Please enter a term to search by") EndIf
This returns "Conversion from string "" to type 'Long' is not valid." I was wondering what the error is and how it's possible to fix it? The other questions that I've looked at were mostly to do with variables assigned incorrect types, but I think that isn't the issue. It occurs when all of the variables are empty.
OK, this is going better, now im stuck in the mud again, i am trying to get a form to print,this works now, however i would like to enable a few frames with text boxes for a few seconds to allow the printer to print the text in black instead of gray. he error i am getting is this, as the timer disables:" Unable to cast object of type System.Windows.Forms.Timer' to type 'System.Windows.Forms.ToolStripMenuItem'. "
I have a field named 'UserID' in my OLE database with the type 'Autonumber'. But when I try to cast it to a variable of type 'String' I get an an InvalidCastException - Specified cast is not value.
Private Sub gvDesignGVnote_CellClick(ByVal sender As System.Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles gvDesignGVnote.CellClick If e.RowIndex < 0 Then[code]......
I'm using a C# API wrapper library for connection to a program. It has worked very well for a long time, but now I have this error I can not get out of. The error occurs inside the library code (which I have not modified). It gives the following pop-up window:I believe I had this or similar type of error some times before (at least the first pop up was similar), and then I believe I just clicked "Build solution", or rebuild, and it would work. But this time not...
I am making a simple calculator and it's saying InvalidCastException was unhandled when I try to debug it, here's the code, please tell me whats wrong with it: (and yes I have renamed the textboxes to addequals etc...
Public Class Form1 Private Sub WebBrowser1_DocumentCompleted(ByVal sender As System.Object, ByVal e As System.Windows.Forms.WebBrowserDocumentCompletedEventArgs) End Sub
I am using Visual Studio 2005, Version 2.0. Coding a windows application with VB.NET.I am trying to use a textbox (txtLogCall) to display matched results in a datagrid. I have added a bindingsource and have the dataset and tableadapter.
I have set the databinding tag of the datagrid to the field that I want to use as a parameter. The textbox is for an Caller's Name, so I have set the datagrid tag to 'EmergencyCallerIdentification' that is in the table.
I have some trouble in SMS gateway project using VB.Net (VS 2010)while programme was running, I found error "InvalidCastException was Unhandled", then my programme cannot continue. below I copy the code of the programme :
---------------------------------------------------------------------------------------------------------------------- Option Explicit On Public Class MessageReceiver Private TPMessageTime As String
I have a Linq Group By query that works. Here's the query:
Dim query = From fb As Feedback In lst Where fb.Seller.login_name.ToLower = UserName.ToLower Order By fb.transaction_id Descending, fb.creation Descending _
[Code]...
I don't like working with anonymous types so I'm trying to delare the result and am hitting an InvalidCastException.
I have a Linq Group By query that works. Here's the query:
Dim query = From fb As Feedback In lst Where fb.Seller.login_name.ToLower = UserName.ToLower Order By fb.transaction_id Descending, fb.creation Descending _ Group fb By fb.transaction_id _ Into Group
I don't like working with anonymous types so I'm trying to delare the result and am hitting an InvalidCastException.
So, armed with this information, here's the declaration used:
Dim query As IEnumerable(Of IGrouping(Of Int32?, IEnumerable(Of Feedback)))
Here's the error returned:
Unable to cast object of type 'System.Linq.GroupedEnumerable`4[Feedback,System.Nullable`1[System.Int32],Feedback,VB$AnonymousType_0`2[System.Nullable`1[System.Int32],System.Collections.Generic.IEnumerable`1[Feedback]]]' to type
I am trying to catch the System.InvalidCastException error. If I put a number into the calculator the program runs ok. If the calculate button is pressed with nothing in the text boxes I get the casting error Conversion from string "" to type 'Decimal' is not valid. I understand why I am getting the error. I don't know what to do about it. I want the program to dump null data and go back to waiting for input from the user.
Private Sub btnCalculate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalculate.Click Dim FedTaxRate = 0.13 ' constants for taxes and work week
I'm programming a slideshow in Visual basic and get a SystemInvalidCastException when trying to initialize an array through a For Each loop. Here's what I'm trying to do. I have an array of Images() and another array of ImageNames(). Now I store all my images on a website, let's sa so for ease of use, I've named all my images in this manner
I've got a typed dataset. I bind the data with a binding source to a form with arround 200 textboxes, dataedits and so on. Everything works fine with one exception:In my database I have empty DateTimes (DBNull.Value). And when they get bound to a DateEdit-Control, I get the following exceptions:
A first chance exception of type 'System.InvalidCastException' occurred in Microsoft.VisualBasic.dll A first chance exception of type 'System.Data.StrongTypingException' occurred in myTestDLL.dll
I tried to change the NullValue-Property in the DataSet-Desinger to something else as 'Throw Exception', but it doesn't work for a DateTime. For other types like Integer or String it works fine.I dont know a nice solution (right now I fill the empty dates with some dummy date and make it invisible in the DateEdit-Control, but this is very uncool) and I hope to find some help here.
I get the correct numbers out of the variable(in this case 11) but i cannot compare it bcuz i get this error. both values are int, cannot seem to find the problem.
Dim id = CInt(Request.QueryString("id")) Dim uk = From hj In dc.Orders _ Where hj.UserID = id _ Select hj
