C# - Binarywriter.flush() Also Flush The Underlying Filestream Object?
Jun 1, 2010
I have got a code snippet as follows:
Dim fstream = new filestream(some file here)
dim bwriter = new binarywriter(fstream)
while not end of file
read from source file
bwriter.write()
bwriter.flush()
end while
The question I have is the following. When I call bwriter.flush() does it also flush the fstream object? Or should I have to explicitly call fstream.flush() such as given in the following example:
[Code]...
A few people suggested that I need to call fstream.flush() explicitly to make sure that the data is written to the disk (or the device). However, my testing shows that the data is written to the disk as soon as I call flush() method on the bwriter object.
I'm working in Visual Basic Express 2008, and have created a little application to run a marquee to display information for our hospital, that will auto-update.
I am trying to position the form to sit flush with the top-right portion of the screen. I set the position manually, to 800,0 which does move it to about the area i'm looking for, but depending on resolution (which varies throughout the facility) it will not sit flush with the right side of the screen.
Is there anyway to set form parameters to right-align?
When should I call the Flush() method (TextWriter.Flush() / StreamWriter.Flush() / BinaryWriter.Flush() / etc) ? Should I call it everytime I finish writing a stream?
This link explains the Encoder.GetBytes Method and there is a bool parameter called flush explained too . The explanation of flush is : true if this encoder can flush its state at the end of the conversion; otherwise, false. To ensure correct termination of a sequence of blocks of encoded bytes, the last call to GetBytes can specify a value of true for flush.but I didn't understand what flush does?
I'm attempting to discard the contents of a System.Net.Sockets.Socket send buffer using theSocket.IOControl(IOControlCode.Flush, .... Does anybody know whether VB.NET supports this command? I've tried supplying 'Nothing' and 'Nothing' for both required parameters, also empty and populated byte arrays in combination with 'Nothing' for both required parameters, but I consistently get an 'Invalid argument' exception. I've tried a web search for an answer, but the only mention I've found was a question asked about 8 years ago, with still no answer.
I have a program that opens a FormReportViewer. I get an error when I close my program...COM object that has been separated from its underlying RCW cannot be used.
I'm designing an ATM where I have to allow a user to "insert" his card and then conduct transactions. After the first user is done, without closing the application, another user should be able to use the ATM. However, whenever I try to log the second user in, I get the following error: COM object that has been separated from its underlying RCW cannot be used.
My code for the opening screen is as follows:
Imports System.Data.OleDb Public Class StartScreen 'Form-wide variables
I've written a custom class MyClass and marked it with the <Serializable()> attribute. I have a set of binary files on my hard drive that I've serialized using BinaryFormatter that came from instances of MyClass.
I've recently changed the structure of MyClass slightly (added some properties, deleted some properties, changed a few methods, etc).
What happens when I try to deserialize the existing objects to this changed class using the code below? I've tried it and not had an error thrown or anything - but surely it can't deserialize properly when the class has changed? Is there a way I can get some useful information out of the serialized files even though I've updated the class?
Here's the code I'm using to do the serialization:
Public Sub serializeObject(ByVal obj As Object, ByVal outFilename As String) Dim fStream As FileStream Try
I'm having this weird issue with the FileStream Object. I'm using this object to render some reports as PDF format.
This is the code;
PrivateSub ExporttoPDF(ByVal NameAsString)
Dim warningsAs Warning() =Nothing
Dim streamidsAsString() =Nothing
[CODE]...
Name is a parameter I'm passing to this subroutine from another one. When the application passes the first name, creates the pdf file fine, on the second name parameter fails to create the pfd file saying that Could not find a part of the path and it showing the path. I don't understand why is doing this.
The goal is to write data to a SQL Server 2008 FILESTREAM file using VB.Net. An "Access Denied" message occurs when creating a FileStream object in the code(see red underlined code below). SQL Server 2008 is configured to "Allow remote clients to have streaming access to FILESTREM data" along with "Enable FILESTREAM for Transaction-SQL access"... What configuration setting is missing and causing the "Access Denied" message? Figure 1.) Code used to stream data to SQL Server managed file
I'm having a problem with converting from one source type to a destination type. I have a form with 2 buttons (button 2 uses the OpenFileDialog to have the user open an excel file set to NewFile),(button 1 takes the contents from specific cells in NewFile and arranges them how I need into oXLApp1).
The error I get is "Unable to cast object of type 'System.IO.FileStream' to type 'Excel.Application'." in line 14 of the code below.
Public Class Form1 Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
I need to write a file that will be built mostly from simple text and divided by "|" but in one of its fields i must to use BinaryWriter to store the string as binary and not a simple text, is there a way to do it?
Can you delete stuff inside of a file after you have committed it to the binary file? I noticed that you can still read the stuff inside of a binary file.Also is there a step by step tutorial for the binaryreader and writer
I have function on client side that get file, make a byte array from it and send that array to the web service on server!This is the function on client side:
How do I get the current write-position using the BinaryWriter. I need to store the position in order to read from that position afterwards. (I know it would give the position where the next write would start, that will be taken care of).
I created a subroutine to copy and paste a file using the binaryreader and binarywriter. It works fine from what I can tell. The file sizes match up any how but I was wondering if anybody had an idea on a better way to get the amount of bytes that should be copied in one set.
binwriter.Write(binread.ReadBytes(100000)) I want to make the readbytes as large as possible without crashing the users computer.
Okay, this actually relates to some work I'm doing that I already have something in place. So if a change is necessary down the road, I'm in no hurry... But I did a dangerous thing and began reading. As I began reading about ways to stream file data, I became curious as to when it is a good idea to one method or the other.
I need to store/retrieve a bit from a data table of 3.268.760 bits long.
Using w As New BinaryWriter(File.Open("test.bin", FileMode.Create)) for x = 1 to 3268760 For i = 1 To 3268760[code]....
the w.write(?) stores a boolean value meaning 0/1 for false/true values, but Vb.net seems to use an whole byte to store this data which is too expensive for my table (3.268.760^2).Is there a pratical way to store/retrive single bits from a file using vb.net? (meaning as little as possible conversion to other types).
I am using BinaryWriter class to write a binary file to disk. When I invoke the Write method, passing an unsigned short value, it writes it in little-endian format. For example:
bw.Write(0xA000);
writes the value in the binary file as 0x00 0xA0. Is there a way to make BInaryWriter use Big Endian? If not, is it possible to create a new class, inheriting BinaryWriter and overload the Write function to make it write big endian?
Is there something like VBA's ScreenUpdating=Off in VB.Net? I mean, I want to manage the underlying data and wish it would not reflect on the screen until the end.
I am retrieving data from my database using a TableAdapter. I was wondering if there is some way I can tell (or be informed) that the data has changed and I therefore need to do another Fill? That way I can just Fill on demand rather than every time the user requests to see the information and I am forced to do a Fill before showing the data because I don't know if is current or not. For the record I am using an ODBC connection string to access a Pervasive PSQL database
EDIT I was thinking I could check the last write time of the MKD file to check if this has changed but this doesn't seem to be reliable as it is not written to until the connection is closed. Does anyone know the circumstances when this is written?
I need to force a DataGridView cell to update the underlying DataTable.I fill a DataTable using my adapters Fill method, then set that DataTable as my DataGridView's datasource. Lets say one of my DataGridView columns is a CheckBox column.If I left-click a checkbox in the first row and then left click a different row in the DataGridView the underlying DataTable_RowChanged event fires, which tells me the first edit I did has gone to the underlying DataTable.If I left-click the checkbox in a row and then right-click the column header to display my context menu the DataTable_ RowChanged event doesn't fire because the DataGridView row is still in edit mode.I've tried Me.DataGridView.EndEdit(),but that doesn't cause my RowChanged event to fire,I need to ensure my underlying DataTable matches the data in the DataGridView, because I am getting a subset of my original table.[code]
I've got a databound query in my application which is querying the "Customers" table in our database.I've created this directly from the ComboBox's datasource creator in the Design view.Various bits of code created in the designer include:
What I've done in the first stage of developing this feature is to show my users a ComboBox showing a specific subset of the customer list by applying a filter to the BindingSource.
What I want to do on a second pass is to allow the users to type a specific bit of information into a textbox and check whether it appears in Me.CustomerDataSet like so:
Dim x As IEnumerable(Of CustomerDataSet.customerRow) = From cust In Me.CustomerDataSet.customer Where cust.custno.Trim = "test" If x.Count <> 0 Then
At this point, I have a customerRow object. I want to check whether this customerRow object appears in the list presented to users in Me.ComboBox_Customers via the filtered Me.CustomerBindingSource. Me.CustomerBindingSource does not (directly) contain customerRow objects, it contains Object objects.How do I find out whether Me.CustomerBindingSource contains the customerRow object at whatever lower level?Also Once I've determined that Me.CustomerBindingSource contains the item, how do I select that entry in the ComboBox?
I have a button on the page and a gridview with checkboxes on the first column. The gridview is bound to a List. On buttonClick, I need to retrieve the underlying bound data item (MyEntity) for each selected row. How can I do this? I can't simply recreate MyEntity based on the gridview columns, because I am not displaying all the fields of MyEntity. I need a way to get a hold of MyEntity based on the key (MyEntityId).
I have an object databound to a WinForm. One property, BOLNumber is bound to a textbox on the form. When you change the value in the form, the underlying BOLNumber property is changed. But the property setter does some "formatting" to the value. I want to BOLNumber textbox to reflect the changes to the value made in the property setter immediately upon the textbox losing focus. I tried implementing the INotifyPropertyChanged interface, but I am either doing something wrong or misunderstanding something it would seem. How do I get the databound control to reflect the changes to the underlying data source?
Public Event PropertyChanged As PropertyChangedEventHandler _ Implements INotifyPropertyChanged.PropertyChanged Public Property BOLNumber As String
I'm looking for a simple example in VB2008 code.I have the Northwind DB installed on one of our SQL servers.
I've worked with the Datagridview on serveral occasions but never used its update,delete or add functions. I've Googled around the web, but could not find a simple example.
Whats the best way to do this and implement it using LINQ?
find the underlying DataGridView (DGV) when responding to a Right Click on a ToolStripMenu (TSM).I have several DGV's all using the same ContextMenuStrip (CMS) [DGV.ContextMenuStrip=CMS]I have six ToolStripMenuItems under the CMS. I thought I could just add a unique handler for each of the ToolStripMenuItems and be a happy camper on each Right Click...But I cannot figure a way to decode the underlying DGV. There doesn't seem to be any relationships between DGV and TSM and none between CMS and TSM.Is this path a dead end? If so how should one do it? FYI my DGV data is unbounded.
I have a Windows Form application with a form that has an underlying data set. When the users click a particular button, the code clears some fields on the form but also is suppose to update a value in the underlying dataset on a field that is NOT displayed on the form.
In VB6 and VBA this is very easy to do. I simply says Forms!formname!NameOfUnderlyingFieldNotshown and pass it the value. How do I do this in VB.net with a Windows Form and underlying dataset?
Re DataGridView Sorry don't really have any code - just a whole project. Basically I changed the underlying Access (accdb) Table by adding a new field, The new field shows up in the DataSources section of the Solution Explorer and in the "Edit DataSet with wizard" page but when I attach the binding source to a datagrid view, the new field is not there. I also created a new bindingsource but still not there.I just noticed I've another table where I changed the names to something more meaningful, and the old names are still there and the data for those fields doesn't display in the DataGridView
