I am having problems getting my program to write to a txt file and also read the info in the file.The program does look for the file and throws an error if the file does not exist but it does not read or write the user info from/to the file. The program does everything else I need it to with this exception.[code]
View 3 RepliesI'm writing a program that basically loads an entire text file into a streamreader variable, then reads this variable line by line and parses and writes a line into a new text file. I'm VERY new and my knowledge is mostly self-taught, but I can't seem to get out of this one. It works for smaller files, but it appears to reach a limit in characters at some point because in a file of 900 lines, it stops writing about halfway through 800 and there are no errors, the program actually completes and the message box pops up.
There are a few things with this code I already know I should fix, such as creating the new text file name, it's messy, I just don't know how.
Private Sub btnProcess_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnProcess.Click
Dim IndexValues As String()
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I've Googled this for a long time but I haven't come across an answer...or I didn't realize it if i did. I need to create an advanced clipboard that will allow you to save 50 phrases for later use. It will have 5 tabs, 10 phrases on each tab with a button next to each phrase to copy. So, the user will open the program; click the appropriate tab then click the button next to a phrase to copy it to the computer's clipboard so they can paste it somewhere else.
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I was able to code a sub that opens a StreamReader and Writer. The Reader reads a *.txt file and the Writer modifies it line by line as it's entered into the memory then writes it to a temporary file which is then copied over the file that the Reader read.
The problem is that the StreamReader and Writer seem to fail to close.At first when I tested it I would get an error stating:
Object reference not set to an instance of an object
I put breakpoints in the sub to figure out where it's erroring out and it's erroring out when it does sr.close() and sw.close() (Reader/Writer.close())Here's the code for the sub. Maybe someone can tell me what I did wrong.
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
If pDebugMessages = True Then MsgBox("Stream Reader/Writer initialized.", MsgBoxStyle.OkOnly, "Debug")
Try
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I have a vb.net function which uses oledb to create a spreadsheet, then treat it like a database, creating tables and inserting values. The function takes in a filename and a dataset, and returns the filename if it worked. The function works beautifully on my dev machine, but not other PCs. Below is my function, is there anything wrong with the code? EDIT: There are no errors being thrown, the resulting file doesn't contain any data.
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I have a problem with a streamreader in visual basic 2008.I am updating a database from text files on an ftp server. The streamreader works fine until the file is more than 100,000 bytes long.It reads until it reaches this point and then just ends. No error message, it just reads to this point which happens to be 2 fields out of 6 in the database stream. My question is - does the streamreader have a limit? And if so what is a workaround?
Dim connString As String = "Data Source=" & pDataBase
conn = New SqlCeConnection(connString)
Dim strQuery As String = ""[code]......
how do you open a text writter? (&keep it open)?
View 4 Replieshow do you open a text writer? (&keep it open)?
View 1 Repliesis it possible to print over a form instead of using a type writer (printing the text in a text box on the correct fields or blank lines)? my attempt i measure the x and y coordinates of the fields where the printer should print the text in centimeters by placing a scale on the form paper and taking the top left corner of the paper as the origin
i fed these x and y values measured with a scale to my vb .net program which:subtracts the height of the font from the y value (assuming the printer prints the topmost pixel of the character first)
and also converts the the centimeters to inches and multiplies them by 100 but when i print these fields over the form they are printed at wrong x and y coordinates for time being i adjusted the values (by trial and error) for 1 particular form but i dont want to do this for every form!!! what am i missing in my calculation that is making the printer print at wrong x and y coordinates?
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I'm using the stream writer to make a text file and write to it.I'm trying to get all the items from the listbox2 and save them to a text file called log.txt.The funny part is that its not giving me a ex.message.Do you see any error.[code]...
View 13 Repliesmy company provides security card for certain seller agents that sold our products to customers. they need to claim their point or login through PDA application by scan barcode or swipe magstripe (magnetic stripe). i had written the code for barcode scanner, and i had written the code for magstripe reader, but it didn't need any comm control at all. all i had to do was focusing on textbox that showed data had read.i had device to write data, it is MSRE206 with serial port. now i need code in VB to write data to magstripe. i didn't have any experience with comm control in VB, so i didn't know where i have to start?how to write a program in VB so that i can write data to a magnetic stripe on cards?
View 9 Repliesi am creating a program which scans and saves images. in my program i have the option to save images and with each image i save it gets its own number for example: file1, file2, file3, file4 and so on. the only problem i have is getting the prgram to remember where it left off so it carry's on the number. my understanding is that i need to create some sort of stream writer or file stream class for this proccess to work. so it save's the last image number i was on, and carrys it on next time i open the program up again. and i also need it to re-write the new image number its on for next time. so i need to write and read the text file (.txt) and write it again if you catch my drift? i have a book to help but the wording in it is so confusing at the min, i m lost where to start.
View 1 Repliesi am working on a project that uses an magnatec card reader mse-750 iam facing a problem in making the machine on read mode so i can read from it iam using vb.net?
View 3 Repliesthis project im working on is giving me a headache. am trying to write a program to recognie both ntfs and ext3 fileformats and enable the copying of files between them. ive done the ntfs bit and my problem is how do i implement the ext3 file system reader and writer using visual basic.net.any references would be really useful.
View 1 RepliesI want to open a file with a stream writer. Delete it contains and write random data to it. And finally delete the file.
View 10 RepliesI am having a strange issue when using the StreamWriter where I am getting some strange charachers in my text file when reading data from a query string.
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The bigger problem is that I can't seem to get everything involving using stream writer and reader working. If I start of with a .txt file already correctly formatted then I can display it in the list box. But adding data during run time is not proving successful.
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I have a dataGridView and tied it to a button that saves every time you click it. and every time you click it, I want to write a line to a txtfile that displays how many records were changed and the date that they were changed. Everything works fine but every time a save has been made it over write the previous entry on the text file. Here is some of the code.
If changes > 0 Then
MessageBox.Show(changes & " changed rows were stored in the database.") ' changes shows how many entries were changed
swDate.WriteLine(changes & " record changes on " & entryDate) 'entryDate is formated as date with value of "Now"
Else
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I am getting the right results in the text file except it over writes previous entry's so there is only one entry saved in the text file at any given time. I want it to keep building the text file so every time something is streamWrited the previous things in the text file stay there and it add to it. Looking at my problem I cant really justify or implement a For Each..Next or a Do While..Loop. My vb knowledge is limited so go easy on me.
Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
Dim PDFFileName, PDFTest As String
Dim PDFNameLength, SlashLocator As Integer
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What is the code to make a stream writer remove a certain line from a file stream?
View 1 RepliesI want to write binary file in loop.To write data to hexadecimal use this function.Private Sub Write (ByVal TargetFile As String, ByVal FileOffset As Long, ByVal NewValue As Byte)
Dim br As BinaryReader = New BinaryReader(File.Open(TargetFile, FileMode.Open))
br.BaseStream.Position = FileOffset
br.BaseStream.WriteByte(NewValue)
br.Close()
End Sub How could i write file using a loop in listbox loaded with hex values? The sequence is repeated every 100 bytes.
I'm wanting to store some settings for my program in an XML document. I've found plenty of places that allow you to write an XML document to somewhere on the hard drive although I'm wanting to link it in with the project so when the program installs it setups up the XML as well. This is also so when the program uninstalls it removes the XML.So I was wondering how I would go about writing to the XML document in my project, could it be done with Linq?
View 2 RepliesI'm trying to setup a simple app that reads a file and then writes the contents to another file using OpenFileDialog and SaveFileDialog. Looking at the debbugger it looks like it's reading fine, I can see the data I want written. Towards the end of my code I get the following error message:"Illegal characters in path". I've researched this error. I'm not using any illegal characters such as /\? etc and the pathname contains all alpha characters. I'm pulling the test file from the C drive and trying to save it there as well.
Path: C:\Test.csv
My code:
Private Sub btnAppendData_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAppendData.Click
Dim Result As DialogResult
Dim FileContents As String
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I am trying to make my application read data from a file. Then save the data back. However I keep getting an error which says the file is still open so cannot be edited. I also read that there is an issue with the streamreader and streamwriter do not close the program straight away. I was wondering if anyone had a way around this or any alternative ideas. Heres my code so far!
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I am new to Visual Basics and I am using Visual Basic 2008 express. I have been using video tutorial on line to learn VB and they are great in explaining what is happening the code vs. just looking at code. I think from what little I can find I would be using StreamWriter WriteLine and StreamReader readLine .I am using a couple of forms. I am looking for simple basic code to use a form as a way of modifying timer intervals and store the values in a single text file on separate lines.
Description:
Form1: will contain the main code that will run. It will contain some timers. I want the timers to look in a text file for their intervals. Each timer would be on a different line.
Example:
Timer1 interval would be located on line 3
Timer2 interval would be located on line 6
Timer3 interval would be located on line 20
Form2: will contain 3 textboxes. This is where when I load form2 I will also read the same values from the text file to preload the text boxes. I will now be able to change the timer intervals as needed and press a button to update the text file. The update button will also reload the new timer settings on Form1. This is very similar to how a CNC Machine works with Parameter settings. This can be useful for storing many different settings for a form that a user can modify and be stored and reloaded next time the program runs.
I'm making a browser and for the favorites I'm using a reader and writer to read and write new favorite to a .txt file. Now if I edit the text file manually and load up the browser, the favorites show up as they should but the problem comes in when I add the a new favourite and then reload the application. Once reloaded the favorites seem to copy what was originally in the file and then whatever I added last at the bottom.
Here is the
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
WebBrowser1.Navigate(TextBox1.Text)
ListBox1.Items.Add(TextBox1.Text)
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I have a program that reads a text file tab delimted using OLEDb .I need to be able to allow the user to insert a user created record into the file which I can do.
The problem is I need to be able to let the user edit that record. From my understanding you can not edit or delete with OLEDB only insert So I thought I would read the file using stream reader, find the line I want to edit and just delete it, rewrite the file, then let the user insert a new record
If someone has a better way to perform this operation I am open its just the best way I could find with my limited knowledge and the reading and researching I have been doing thus far.
So I am trying to step-by step and first read the file which seems to work then find the line that would need to be deleted. So I was trying to use the
line.startswith method. I am using msgbox to see if that works before I continue but it doesnt seem to work I know my file has several lines starting with "Active" but my msgbox returns "False"
Here is the code I have so far
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We needed an inter-process reader/writer lock.We decided to use a file and lock the first byte using LockEx and UnlockEx. The class creates a file in the system temp folder when it is created. The file is created with readwrite access and share read|write|delete.We also specify DeleteOnClose so we don't leave loads of temp files laying around. Obviously AcquireReader and AcquireWriter call LockEx with appropriate flags and ReleaseLock calls UnlockEx.We have tested this class using a small application that you can run several instances of and it works perfectly. The application that uses it has a problem, which we have managed to re-produce in another small test app. In pseudo code it is
Create InterProcessReaderWriter
Dispose InterProcessReaderWriter without acquiring any locks
Launch a child process which takes a reader lock
The first time this runs, it works fine. If you attempt to run it again, while the child process from the first time is still holding the lock, we get an UnauthorisedAccessException when trying to open the file.This appears to be a permission issue, not a sharing violation but all the processes in this test case are running as the same user.
I have a smart card reader/writer hooked up to my serial port. i've already coded the program to give access to the serial port. How would I go about getting my Card Reader/writer recognized in my program. I basically want to click the "read button" and whatever is on the current smart card im trying to read, pop up on the screen.
View 1 RepliesI have an asp page with vb.net code that will query a database and present the user with the number of records that exist that need to be exported along with a button to export them. After you push the export button, it will prompt for a location and filename. But after that, it will not refresh the page with the new counts that now exist. Or in this case update the count to zero for the button they clicked.
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So how can I tell the page to refresh with the new counts. It almost seems like I need to tell the process to wait until after the user has finished finding the location and saving the file but I don't want to add a generic threading.thread.sleep in, I want it to only wait until they are done and then refresh the page.