I am trying to outside text to a log file for my application. But every time it tries I get the error shown in the image :/
Here is the code I'm using:
Dim exporter As New StreamWriter("C:\log.txt")
exporter = My.Computer.FileSystem.OpenTextFileWriter("c:\log.txt", True)
exporter.WriteLine(log)
exporter.Close()
Try to do that (This code will replace de entire file. if you want to append, you'll need to read de actual value and then write or just use the append function):
Using exporter = New StreamWriter("C:\log.txt")
exporter.WriteLine(log)
End Using
The issue happens because you are using the file two times. The first one when you put New StreamWriter, e the second one when you OpenTextFileWriter before close the first one.
Related
Is it possible for the following code to produce NUL values within a text file?
var temp_str = "123456;1234567"
My.Computer.FileSystem.WriteAllText(Path & "stats.txt", temp_str, False)
It seems simple, but it writes quite often and I'm seeing several files that get accessed by the application that have Strings written to as:
When opening the file with Notepad++. Some other editors show just squares, and it seems like each character is represented by a block/NUL.
So far I've been unable to reproduce this on my test system. I just find the files on a COMX module's file system that's been running in the field and comes back faulty, but I've been seeing enough of these files to make it a problem that needs to be solved.
Does anyone have an idea to prevent this behaviour?
Hard to say what the problem is without more code, but try this if you want to replace the existing contents of the file:
Dim fileContent = "My UTF-8 file contents"
Using writer As IO.StreamWriter = IO.File.CreateText(fullPathIncludingExtension)
writer.Write(fileContent)
End Using
Or this if you want to append UTF-8 text:
Dim newLines = "My UTF-8 content to append"
Using writer As IO.StreamWriter = IO.File.AppendAllText(fullPathIncludingExtension)
writer.Write(fileContent)
End Using
If you want to append Unicode text, you must use a different constructor for StreamWriter:
Using writer As IO.StreamWriter = New IO.StreamWriter("full/path/to/file.txt", True, Text.Encoding.Unicode)
writer.Write(MyContentToAppend)
End Using
Note that the True argument to the constructor specifies that you want to append text.
On a button click I have the following code to write what Is in my textboxes.
Dim file As System.IO.StreamWriter
file = My.Computer.FileSystem.OpenTextFileWriter("C:/Users/Nick/Documents/Dra.txt", False)
file.WriteLine(NameBasic)
file.WriteLine(LastBasic)
file.WriteLine(PhoneBasic)
file.WriteLine(NameEmer1)
On my form load, I load what is in the notepad from what was written, It is saying It is already being used(the file) which is true, how can I have two different functions(write, and read) manipulating the same file with out this error?
The process cannot access the file 'C:\Users\Nick\Documents\Dra.txt' because it is being used by another process.
And here is the code for my onformload
Dim read As System.IO.StreamReader
read = My.Computer.FileSystem.OpenTextFileReader("C:/Users/Nick/Documents/Dra.txt")
lblNameBasic.Text = read.ReadLine
I am sort of stuck on this problem, thank you
You need to close the file when you are done writing to it.
Dim file As System.IO.StreamWriter
file = My.Computer.FileSystem.OpenTextFileWriter("C:/Users/Nick/Documents/Dra.txt", False)
file.WriteLine(NameBasic)
file.WriteLine(LastBasic)
file.WriteLine(PhoneBasic)
file.WriteLine(NameEmer1)
file.Close()
To answer your question:
how can I have two different functions(write, and read) manipulating the same file with out this error?
If you really want to simultaneously read and write to the same file from two processes, you need to open the file with the FileShare.ReadWrite option. The My.Computer.FileSystem methods don't do that.¹
However, I suspect that you don't really wan't to do that. I suspect that you want to write and, after you are finished writing, you want to read. In that case, just closing the file after using it will suffice. The easiest way to do that is to use the Using statement:
Using file = My.Computer.FileSystem.OpenTextFileWriter(...)
file.WriteLine(...)
file.WriteLine(...)
...
End Using
This ensures that the file will be closed properly as soon as the Using block is left (either by normal execution or by an exception). In fact, it is good practice to wrap use of every object whose class implements IDisposable (such as StreamWriter) in a Using statement.
¹ According to the reference source, OpenTextFileWriter creates a New IO.StreamWriter(file, append, encoding), which in turn creates a new FileStream(..., FileShare.Read, ...).
I'm sure this is really simple, but has had me stumped for a while!
I need to show the user a text file, with lines being written to it as my program executes. Stuff like "Working on this file - Successful!". Another forum thread has helped me to allow the text file to be accessed by multiple processes, but now when I open the text file using Process.Start, it doesn't show the lines that are being written using the StreamWriter. Any help very much appreciated.
Code:
Dim ExportLog As String = "C:\ExportLog.txt"
If System.IO.File.Exists(ExportLog) Then
System.IO.File.Delete(ExportLog)
End If
Using writeStream = System.IO.File.Open(ExportLog,
FileMode.OpenOrCreate, FileAccess.ReadWrite,
FileShare.ReadWrite), Write As New StreamWriter(writeStream)
Write.WriteLine("Starting")
End Using
Dim MyLog As Process = Process.Start(ExportLog)
I have this txt file with the following information:
National_Insurence_Number;Name;Surname;Hours_Worked;Price_Per_Hour so:
eg.: aa-12-34-56-a;Peter;Smith;36;12
This data has been inputed to the txt file through a VB form which works totally fine, the problem comes when, on another form. This is what I expect it to do:
The user will input into a text box the employees NI Number.
The program will then search through the file that NI Number and, if found;
It will fill in the appropriate text boxes with its data.
(Then the program calculates tax and national insurance which i got working fine)
So basically the problem comes telling the program to search that NI number and introduce each ";" delimited field into its corresponding text box.
Thanks for all.
You just need to parse the file like a csv, you can use Microsoft.VisualBasic.FileIO.TextFieldParser to do this or you can use CSVHelper - https://github.com/JoshClose/CsvHelper
I've used csv helper in the past and it works great, it allows you to create a class with the structure of the records in your data file then imports the data into a list of these for searching.
You can look here for more info on TextFieldParser if you want to go that way -
Parse Delimited CSV in .NET
Dim afile As FileIO.TextFieldParser = New FileIO.TextFieldParser(FileName)
Dim CurrentRecord As String() ' this array will hold each line of data
afile.TextFieldType = FileIO.FieldType.Delimited
afile.Delimiters = New String() {";"}
afile.HasFieldsEnclosedInQuotes = True
' parse the actual file
Do While Not afile.EndOfData
Try
CurrentRecord = afile.ReadFields
Catch ex As FileIO.MalformedLineException
Stop
End Try
Loop
I'd recommend using CsvHelper though, the documentation is pretty good and working with objects is much easier opposed to the raw string data.
Once you have found the record you can then manually set the text of each text box on your form or use a bindingsource.
i want to create a notepad in this format
100001|10001|1001|91|9942321400|MR|Hari|Q|PUBLIC|249 MUNDON ROAD|MALDON|FL|44|TN|NO_PROVINCE|600004|IN|M|27304|9942321400|test#test.com|nothing|COMMENTS|1|Southeast
100001|10001|1001|91|9865015695|MR|Hari|Q|PUBLIC|249 MUNDON ROAD|MALDON|FL|44|TN|NO_PROVINCE|600004|IN|M|27304|9942321400|test#test.com|nothing|COMMENTS|1|Southeast
100001|10001|1001|91|9894825469|MR|Hari|Q|PUBLIC|249 MUNDON ROAD|MALDON|FL|44|TN|NO_PROVINCE|600004|IN|M|27304|9942321400|test#test.com|nothing|COMMENTS|1|Southeast
am using vb.net,in the above format except phone number remaining values are same.and it would be written in to the notepad with pipeline separator.
phone number values are recieved from dataset and store it in a variable . with in looping am use stream writer statement. but am not able to get the output. please help me to do this? am new to vb.net
Try something like that to write your file.
Import System.IO and add that routine. The Path should be the complete path including the file name and extension of the file you want to generate. If you change False to True it will append the text at the final of the file if you write it again, with false it overwrite it.
Using writer As StreamWriter = New StreamWriter(path, False, System.Text.Encoding.UTF8)
for each ...
writer.writeLine(var1+"|"+var2...)
Next
writer.Close()
End Using