.net-3.5

问题 Coming from Basic boolean logic in C# , I was wondering why: Dim b As Boolean Dim obj As Object = Nothing 'followig evaluates to False' b = DirectCast(Nothing, Boolean) 'This throws an "Object reference not set to an instance of an object"-Exception' b = DirectCast(obj, Boolean) A CType(obj, Boolean) would evaluate to False (just as CBool(obj)) . I think it is because the compiler uses a helper function, but that is not my theme. Why does casting Nothing to Boolean evaluates to False ,

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 4 years ago . Anyone know a good book or post about how to start in EF? I have seen the DnrTV any other place? 回答1: Mike Taulty's Blog: http://mtaulty.com/CommunityServer/blogs/mike_taultys_blog/archive/category/1024.aspx A great EF intro deck: http://mtaulty.com/CommunityServer/blogs/mike_taultys_blog/archive/2008/03/13

问题 I am currently working with a ASP.NET Web site project in Visual Studio 2008 and everytime I make a change to code behind page for a user control and browse to page that is using the user contorl I get the following error: Unable to cast object of type 'ASP.basepage_master' to type 'ASP.basepage_master'. I have to rebuild my entire solution to order to resolve this error. Has anyone else experienced this error and do they know how to resolve it? 回答1: Deleting your temporary ASP.NET files

问题 I am currently working with a ASP.NET Web site project in Visual Studio 2008 and everytime I make a change to code behind page for a user control and browse to page that is using the user contorl I get the following error: Unable to cast object of type 'ASP.basepage_master' to type 'ASP.basepage_master'. I have to rebuild my entire solution to order to resolve this error. Has anyone else experienced this error and do they know how to resolve it? 回答1: Deleting your temporary ASP.NET files

问题 So I'm trying to use a WPF User Control to generate a ton of images from a dataset where each item in the dataset would produce an image... I'm hoping I can set it up in such a way that I can use WPF databinding, and for each item in the dataset, create an instance of my user control, set the dependency property that corresponds to my data item, and then draw the user control to an image, but I'm having problems getting it all working (not sure whether databinding or drawing to the image is

问题 I have the following code: SHChangeNotifyEntry changeentry = new SHChangeNotifyEntry(); changeentry.pIdl = GetPidlFromFolderID(this.Handle, CSIDL.CSIDL_DESKTOP); changeentry.Recursively = true; uint notifyid = SHChangeNotifyRegister( this.Handle, SHCNF.SHCNF_PATHA , SHCNE.SHCNE_ALLEVENTS, WM_SHNOTIFY, 1, ref changeentry); My code is crashing at the SHChangeNotifyRegister. I am trying to register a form for file change notification in Windows Mobile. I think I may be passing incorrect

问题 I have the following code: SHChangeNotifyEntry changeentry = new SHChangeNotifyEntry(); changeentry.pIdl = GetPidlFromFolderID(this.Handle, CSIDL.CSIDL_DESKTOP); changeentry.Recursively = true; uint notifyid = SHChangeNotifyRegister( this.Handle, SHCNF.SHCNF_PATHA , SHCNE.SHCNE_ALLEVENTS, WM_SHNOTIFY, 1, ref changeentry); My code is crashing at the SHChangeNotifyRegister. I am trying to register a form for file change notification in Windows Mobile. I think I may be passing incorrect

问题 I am loading a large result set of about 3 million rows (ADODB record set) into a data table. Its taking too long to even load the result set into a data table. I want to find out a way of extracting only part of a result set and then loading it into a DataTable. Alternatively, is there a way to directly read the recordset directly instead of loading it into a data table and then reading it ? This is the code I use to fill my DataTable - OleDbDataAdapter oleDA = new OleDbDataAdapter();

问题 I'm currently working with C# and I have the following code to set a ComboBox column inside a DGV: // Add the values of the combo box dgvcbGeneric.DataSource = dtDataSource; dgvcbGeneric.ValueMember = "ID"; dgvcbGeneric.DisplayMember = "Value"; dgvcbGeneric.DataPropertyName = strColumn; dgvcbGeneric.DisplayStyle = DataGridViewComboBoxDisplayStyle.ComboBox; dgvcbGeneric.DisplayStyleForCurrentCellOnly = true; // vGenericCMB.SortMode = DataGridViewColumnSortMode.Automatic dgvcbGeneric

问题 alt text http://akashkava.com/blog/wp-content/uploads/2009/12/ListBoxItem-Selection-Problem.png The following code, behaves little strange. <ListBox SelectionMode="Multiple"> <StackPanel> <TextBlock>Selection is Black</TextBlock> </StackPanel> <ListBoxItem> <StackPanel> <TextBlock>Selection is White</TextBlock> </StackPanel> </ListBoxItem> </ListBox> Note that first selection stays in black color, that is because the Item is not its own ItemContainer, however in 2nd case Item is its own