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I work on a project "SignInLogeIn" using Visual Basic.NET.
I save the user informations in text file.
the name of the file is "data.txt".
to create a new account in my program. you must enter the name,email,password and the program write the informations in textfile.
i use "Streamwritter" to write the informations.
when user create a new account The program checks if the email entered by the user is already in the text file that contains the users' information.
and the program checks from informations by "StreamReader". it reads the information in text file and checks.
I have the problem.
when I CREATE A new account. problem appears.
and the problem is
"
An unhandled exception of type 'System.IO.IOException' occurred in mscorlib.dll
Additional information: The process cannot access the file 'D:\1- Anas Files\Projects\VisualBasic.NET\SignInLogIn\SignInLogIn\SignInLogIn\bin\Debug\Data.txt' because it is being used by another process.
"
I think the problem is that I used the file twice
Once to write and once to read.
The error occurs in this line "Dim sw As New StreamWriter("Data.txt")".
how can i solve this problem ?
this is the code of "SignIn" button
Private Sub btnSignIn_Click(sender As Object, e As EventArgs) Handles btnSignIn.Click
Dim strEmail As String = txtEmail.Text
Dim Reg As New Regex("^\w+([-_.]\w+)*#\w+([-.]\w+)*\.\w+([-.]\w+)*$")
If txtUserName.Text.Trim() = "" Or txtEmail.Text.Trim() = "" Or txtPassword.Text.Trim() = "" Then
MsgBox("Please Enter All Input")
If Not Reg.IsMatch(strEmail) Then
MsgBox("Please Enter Email")
End If
Else
Dim sr As New StreamReader("Data.txt")
Dim sw As New StreamWriter("Data.txt")
Dim strPerson As String = txtUserName.Text & ";" & txtEmail.Text & ";" & txtPassword.Text
Dim line As String = ""
Do
line = sr.ReadLine()
Dim arrData As String() = line.Split(";")
If arrData(1) = strEmail Then
MsgBox("Please Change Email")
Else
sw.WriteLine(strPerson)
sw.Close()
End If
Loop While line <> Nothing
sr.Close()
End If
End Sub
You open twice the same file. First, to read and second to write, this is why you cannot write.
Dim sr As New StreamReader("Data.txt")
Dim lines As String = sr.ReadToEnd().Split(Environment.NewLine)
sr.Close()
Dim strPerson As String = txtUserName.Text & ";" & txtEmail.Text & ";" & txtPassword.Text
Dim sw As New StreamWriter("Data.txt")
For Each line As String In lines
Dim arrData As String() = line.Split(";")
If arrData(1) = strEmail Then
MsgBox("Please Change Email")
Exit For
Else
sw.WriteLine(strPerson)
Exit For
End If
Next
sw.Close()
Streams need to be closed and disposed. They are usually put in Using blocks.
I wasn't quite sure of the program flow you wanted. It seemed, since you created a writer and a reader you intended to add to user to the file if they were not listed.
I broke out some of the code into separate methods. I used System.IO since we have a simple text file.
Private Sub btnSignIn_Click(sender As Object, e As EventArgs) Handles btnSignIn.Click
If ValidInput() Then
Dim strPerson As String = $"{txtUserName.Text};{txtEmail.Text};{txtPassword.Text}"
If Not IsUserInFile(strPerson) Then
File.AppendAllText("Data.txt", strPerson & Environment.NewLine)
End If
End If
End Sub
Private Function ValidInput() As Boolean
Dim strEmail As String = txtEmail.Text
Dim Reg As New Regex("^\w+([-_.]\w+)*#\w+([-.]\w+)*\.\w+([-.]\w+)*$")
If txtUserName.Text.Trim() = "" OrElse txtEmail.Text.Trim() = "" OrElse txtPassword.Text.Trim() = "" Then
MsgBox("Please Enter All Input")
Return False
If Not Reg.IsMatch(strEmail) Then
MsgBox("Please Enter Email")
Return False
End If
End If
Return True
End Function
Private Function IsUserInFile(Person As String) As Boolean
Dim p = Person.Split(";"c)
Dim lines = File.ReadAllLines("Data.txt")
For Each line In lines
If Person = line Then
Return True
End If
Dim fields = line.Split(";"c)
If fields(0) = p(0) AndAlso fields(2) = p(2) AndAlso fields(1) <> p(1) Then
MessageBox.Show("Please Change Email")
Return False
End If
Next
Return False
End Function
This is going to get messy and slow if there are too many users. This info should really be in a database. The worst thing is the passwords should always be salted and hashed; never stored as plain text even is a database.
My code downloads files in loop but after the last file downloads it keeps downloading files that aren't there. Website shows redirect and 404 error.
I'm new with visual basic so I'm asking for help here.
My.Computer.Network.DownloadFile(strFullUrlDownload, strFullSavePath, False, 1000)
404 error
redirect
Public Class Form1
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim strMainUrl As String = "http://jixxer.com/123/"
Dim dt As DateTime = DateTime.Now
Dim dtDate As String = dt.ToString("yyyy-MM-dd")
Dim strSlash As String = "/"
Dim strPdf As String = "pdf"
Dim strDot As String = "."
Dim strPage As String = "page"
Dim strPageNbr As String = 1
Dim intCounter As Integer = 1
Dim strPageCounter As String = String.Format("{0:000}", intCounter)
Dim strSavePath As String = "D:\dls\title1\"
Dim strFullSavePath As String = strSavePath & strPageCounter & strDot & strPdf
Dim strFullUrlDownload As String = strMainUrl & dtDate & strSlash & strPdf & strSlash & strPage & strPageNbr & strDot & strPdf
Do Until strPageCounter = 200
' Downloads the resource with the specified URI to a local file.
My.Computer.Network.DownloadFile(strFullUrlDownload, strFullSavePath, False, 1000)
intCounter = intCounter + 1
strPageNbr = strPageNbr + 1
strPageCounter = String.Format("{0:000}", intCounter)
strFullSavePath = strSavePath & strPageCounter & strDot & strPdf
strFullUrlDownload = strMainUrl & dtDate & strSlash & strPdf & strSlash & strPage & strPageNbr & strDot & strPdf
Loop
End Sub
End Class
Try
'TRY to download the file using https first...
My.Computer.Network.DownloadFile(New Uri("https://" & ServerAddress & WebLogoPath & Convert.ToString(RowArray(0)) & ".png"), Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData) & "\" & AppDataFolder & PCLogoPath & Convert.ToString(RowArray(0)) & ".png", "", "", False, 500, True)
Catch ex_https As Exception
'Unable to locate file or write file
'If the operation timed out...
If (ex_https.Message = "The operation has timed out") Then
'Re-TRY to download the file using http instead, as a time out error may indicate that HTTPS is not supported.
Try
My.Computer.Network.DownloadFile(New Uri("http://" & ServerAddress & WebLogoPath & Convert.ToString(RowArray(0)) & ".png"), Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData) & "\" & AppDataFolder & PCLogoPath & Convert.ToString(RowArray(0)) & ".png", "", "", False, 500, True)
Catch ex_http As Exception
'Most likely, the file doesn't exist on the server. Either way, we cannot obtain the file so we need to perform the same action,
'which is handled outside of this Try block.
End Try
Else
'This is most likely a 404 error. Either way, we cannot obtain the file (and the connection is not timing out) - so
'we need to perform the same action, which is handled outside of this Try block.
End If
End Try
I just put the counter at 200 to test and make sure it works. But I know I need a way to quit on error but not sure how to code it yet. Appreciate any help.
If you don't know how many documents are stored in that remote directory, you have to handle the exception when a page is not found.
It's always possible to receive WebExceptions when a resource is requested from a site, so you should handle this case anyway.
I suggest to use the WebClient class directly instead of Network.DownloadFile(), which may be handy if you want to show a predefined UI of the progress (when it's possible), but using WebClient directly, lets you perform the download asynchrounously if you need it to, using the async/await pattern and the WebClient.DownloadFileTaskAsync() method.
Another suggestion: use a method to download those files, so you can call it from anywhere in your code. You can use a class or a module to store your methods, so you don't clutter your UI and you can also easily reuse these classes or modules in different projects, just including in a project the file that contains them.
Your code could be modified as follow (synchronous version):
You need to pass to the DownloadPdfPages method the remote base address: http://jixxer.com/123, the Path where the files are store (filesPath).
The third and fourth parameters are optional:
- If you don't specify a resourceName, Date.Now.ToString("yyyy-MM-dd") is assumed,
- If you don't specify a startPage, it will default to 1, converted in page1.pdf (the example here asks to start from page 3).
Note: I'm using String Interpolation here: $"page{startPage + pageCount}.pdf".
If your VB.Net version doesn't support it, use String.Format() instead.
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim numberOfPages = DownloadPdfPages("http://jixxer.com/123", "D:\dls\title1", "", 3)
If numberOfPages > 0 Then
MessageBox.Show($"Download completed. Number of pages: {numberOfPages}")
Else
MessageBox.Show("Download failed")
End If
End Sub
Private Function DownloadPdfPages(baseAddress As String, filesPath As String, Optional resourceName As String = "", Optional startPage As Integer = 1) As Integer
If String.IsNullOrEmpty(resourceName) Then resourceName = Date.Now.ToString("yyyy-MM-dd")
Dim resourceAddr = Path.Combine(baseAddress, resourceName, "pdf")
Dim pageCount = 0
Dim client = New WebClient()
Try
Do
Dim documentName = $"page{startPage + pageCount}.pdf"
Dim resourceUri = New Uri(Path.Combine(resourceAddr, documentName), UriKind.Absolute)
Dim fileName = Path.Combine(filesPath, documentName)
client.DownloadFile(resourceUri, fileName)
pageCount += 1
Loop
Catch ex As WebException
If ex.Response IsNot Nothing Then
Dim statusCode = DirectCast(ex.Response, HttpWebResponse).StatusCode
If statusCode = HttpStatusCode.NotFound Then
Return pageCount
End If
ElseIf ex.Status = WebExceptionStatus.ProtocolError AndAlso ex.Message.Contains("404") Then
Return pageCount
Else
' Log and/or ...
Throw
End If
Return 0
Finally
client.Dispose()
End Try
End Function
Asynchronous version, using the WebClient.DownloadFileTaskAsync() method.
Just a few changes ae necessary, note the Async keyword added to both the Button.Click handler and the DownloadPdfPagesAsync() method.
The Await keyword is then used to wait for a method to complete, without blocking the UI:
Private Async Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim numberOfPages = Await DownloadPdfPagesAsync("http://jixxer.com/123", "D:\dls\title1", "", 3)
If numberOfPages > 0 Then
MessageBox.Show($"Download completed. Number of pages: {numberOfPages}")
Else
MessageBox.Show("Download failed")
End If
End Sub
Private Async Function DownloadPdfPagesAsync(baseAddress As String, filesPath As String, Optional resourceName As String = "", Optional startPage As Integer = 1) As Task(Of Integer)
If String.IsNullOrEmpty(resourceName) Then resourceName = Date.Now.ToString("yyyy-MM-dd")
Dim resourceAddr = Path.Combine(baseAddress, resourceName, "pdf")
Dim pageCount = 0
Dim client = New WebClient()
Try
Do
Dim documentName = $"page{startPage + pageCount}.pdf"
Dim resourceUri = New Uri(Path.Combine(resourceAddr, documentName), UriKind.Absolute)
Dim fileName = Path.Combine(filesPath, documentName)
Await client.DownloadFileTaskAsync(resourceUri, fileName)
pageCount += 1
Loop
Catch ex As WebException
If ex.Response IsNot Nothing Then
Dim statusCode = DirectCast(ex.Response, HttpWebResponse).StatusCode
If statusCode = HttpStatusCode.NotFound Then
Return pageCount
End If
ElseIf ex.Status = WebExceptionStatus.ProtocolError AndAlso ex.Message.Contains("404") Then
Return pageCount
Else
' Log and/or ...
Throw
End If
Return 0
Finally
client.Dispose()
End Try
End Function
Do
Do
Console.WriteLine("Create a password. It must be 8 characters in length")
password1 = Console.ReadLine()
Loop Until password1.Length = 8
Console.WriteLine("Please re-enter the password.")
password2 = Console.ReadLine()
Loop Until password2 = password1
password = password1
Console.WriteLine("your password has been created.")
Console.ReadLine()
The below code generates the file
Dim fileName = "C:\Users\emily\Documents\Details.csv"
Dim fileAppend As New System.IO.StreamWriter(fileName, True)
fileAppend.WriteLine(name & ", " & age & ", " & username & ", " & password & ", " & yeargroup)
fileAppend.Close()
So basically I have details about the users stored in a csv file. The columns are arranged as follows: name, age, username, password, yeargroup. I need to be able to input a username and for it to be found in the array/list and then input the password and if the password doesn't match for it to start again.
Nice homework. You should think about storing password. Clear text is obviously risky. With the user file load in a table like this will let you manage all of the user. Add,Remove, Change then just save over the userfile.
Public Class Form1
Dim UserTable As New DataTable("UserTable")
Dim SomeUserName As String = "slims"
Dim SomePassword As String = "abc1234!"
Sub ReadUserFile()
Dim fileName = "C:\dump\test.csv"
Dim fileReader As New System.IO.StreamReader(fileName)
UserTable.Columns.Add("Name")
UserTable.Columns.Add("Age")
UserTable.Columns.Add("Username")
UserTable.Columns.Add("Password")
UserTable.Columns.Add("YearGroup")
Do Until fileReader.EndOfStream = True
Dim OneLine As String = fileReader.ReadLine()
UserTable.Rows.Add(OneLine.Split(","))
Loop
fileReader.Close()
End Sub
Sub WriteUserFile()
Dim fileName = "C:\dump\test.csv"
Dim fileWriter As New System.IO.StreamWriter(fileName)
For Each xRow As DataRow In UserTable.Rows
fileWriter.WriteLine(String.Format("{0},{1},{2},{3},{4}", xRow("Name"), xRow("Age"), xRow("Username"), xRow("Password"), xRow("YearGroup")))
Next
fileWriter.Close()
End Sub
Function CheckUserPassword(UserName As String, Password As String) As Boolean
Dim Found As Boolean = False
For Each xRow As DataRow In UserTable.Rows
If (xRow("Username") = SomeUserName) And (xRow("Password") = SomePassword) Then
Found = True
Exit For
Else
Found = False
End If
Next
Return Found
End Function
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
ReadUserFile()
If CheckUserPassword(SomeUserName, SomePassword) = True Then
'Good to go
Else
'bad user/pass
End If
WriteUserFile()
End Sub
End Class
You can use IO.File.ReadAllLines(fileName) to read the lines into an array of strings. Then you can use String.Split() on each line to split the fields and pick out the username and password.
dim allLines as String() = IO.File.ReadAllLines(fileName)
for each line as String in allLines
dim lineArray() as string
lineArray = line.Split(New Char() {","c})
username = lineArray(2)
password = lineArray(3)
if username = theUsernameYouWant then
'Found the user. Now check their password
endif
next
I havn't tested this code. Might have syntax errors.
So I'm still a bit of a newbie when it comes to programming, hence why I'm using visual basic. I'm getting this exception raised repeatedly, but the variables that vb is saying have unassigned values have been given values in my code. Can anyone point out where I'm going wrong with this?
EDIT: just a few more details: the file exists, I can read from it using just the ReadLine method, but I need to split the fields so I can compare the scores and get the highest 2 scores
Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
Dim srdFile As System.IO.StreamReader
Dim strLine As String
Dim strField(1) As String
Dim strName() As String
Dim strScore() As String
Dim i = 0
srdFile = New System.IO.StreamReader("HighScores.dat")
rtbOut.AppendText("HighScores:" & vbNewLine & vbNewLine)
Do Until srdFile.Peek() = -1
strLine = srdFile.ReadLine()
strField = strLine.Split(",")
strName(i) = strField(0)
strScore(i) = strField(1)
rtbOut.AppendText(strName(i) & ", " & strScore(i) & vbNewLine)
i = i + 1
Loop
End Sub
Following two arrays are never initialized: strName and strScore
I don't know the logic, but one way would be to use a List(Of String) instead which does not need to get the correct size in the first place and can be resized. I would also use the Using-statement to dispose the stream properly:
Using srdFile As New System.IO.StreamReader("HighScores.dat")
Dim strLine As String
Dim strField(1) As String
Dim strName As New List(Of String)
Dim strScore As New List(Of String)
Dim i = 0
rtbOut.AppendText("HighScores:" & vbNewLine & vbNewLine)
Do Until srdFile.Peek() = -1
strLine = srdFile.ReadLine()
strField = strLine.Split(","c)
strName.Add(strField(0))
strScore.Add(strField(1))
rtbOut.AppendText(strName(i) & ", " & strScore(i) & vbNewLine)
i += 1
Loop
End Using
Side-note: i recommend to set Option Strict to On by default.
By the way, here is a completely different approach doing the same but with LINQ:
Dim lines = From line In IO.File.ReadLines("HighScores.dat")
Where Not String.IsNullOrWhiteSpace(line)
Let fields = line.Split(","c)
Let name = fields.First()
Let score = fields.Last()
Select String.Format("{0}, {1}", name, score)
rtbOut.Text = String.Join(Environment.NewLine, lines)
I find this more readable.
Before you use an array, you need to assign a fixed array size in the computer memory locations. You can do this by initialising an array with the number of array elements. In your code, you have not allocated any memory to strName() and strScore() before using them, hence the code will throw an exception.
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim srdFile As System.IO.StreamReader
Dim strLine As String
Dim strField(1) As String
Dim strName(10) As String ''fixed size array (Using List(Of T) is a better option)
Dim strScore(10) As String ''fixed size array (Using List(Of T) is a better option)
Dim i = 0
srdFile = New System.IO.StreamReader("HighScores.dat")
rtbOut.AppendText("HighScores:" & vbNewLine & vbNewLine)
Do Until srdFile.Peek() = -1
strLine = srdFile.ReadLine()
strField = strLine.Split(",")
strName(i) = strField(0)
strScore(i) = strField(1)
rtbOut.AppendText(strName(i) & ", " & strScore(i) & vbNewLine)
i = i + 1
Loop
End Sub
You can also create a dynamic array. Please follow Resizing an array at runtime in VB.NET on Stackoverflow about dynamic array.
I have such kind of data in a text file:
12343,M,Helen Beyer,92149999,21,F,10,F,F,T,T,T,F,F
54326,F,Donna Noble,92148888,19,M,99,T,F,T,F,T,F,T
99999,M,Ed Harrison,92147777,28,F,5,F,F,F,F,F,F,T
88886,F,Amy Pond,92146666,31,M,2,T,F,T,T,T,T,T
37378,F,Martha Jones,92144444,30,M,5,T,F,F,F,T,T,T
22444,M,Tom Scully,92145555,42,F,6,T,T,T,T,T,T,T
81184,F,Sarah Jane Smith,92143333,22,F,5,F,F,F,T,T,T,F
97539,M,Angus Harley,92142222,22,M,9,F,T,F,T,T,T,T
24686,F,Rose Tyler,92142222,22,M,5,F,F,F,T,T,T,F
11113,F,Jo Grant,92142222,22,M,5,F,F,F,T,T,T,F
I want to extract the Initial of the first name and complete surname. So the output should look like:
H. Beyer, M
D. Noble, F
E. Harrison, M
The problem is that I should not use String Split function. Instead I have to do it using any other way of string handling.
This is my code:
Public Sub btn_IniSurGen_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn_IniSurGen.Click
Dim vFileName As String = "C:\temp\members.txt"
Dim vText As String = String.Empty
If Not File.Exists(vFileName) Then
lbl_Output.Text = "The file " & vFileName & " does not exist"
Else
Dim rvSR As New IO.StreamReader(vFileName)
Do While rvSR.Peek <> -1
vText = rvSR.ReadLine() & vbNewLine
lbl_Output.Text += vText.Substring(8, 1)
Loop
rvSR.Close()
End If
End Sub
You can use the TextFieldParserClass. It will parse the file and return the results directly to you as a string array.
Using MyReader As New Microsoft.VisualBasic.FileIO.
TextFieldParser("c:\logs\bigfile")
MyReader.TextFieldType =
Microsoft.VisualBasic.FileIO.FieldType.Delimited
MyReader.Delimiters = New String() {","}
Dim currentRow As String()
'Loop through all of the fields in the file.
'If any lines are corrupt, report an error and continue parsing.
While Not MyReader.EndOfData
Try
currentRow = MyReader.ReadFields()
' Include code here to handle the row.
Catch ex As Microsoft.VisualBasic.FileIO.MalformedLineException
MsgBox("Line " & ex.Message &
" is invalid. Skipping")
End Try
End While
End Using
For your wanted result, you may changed
lbl_Output.Text += vText.Substring(8, 1)
to
'declare this first
Dim sInit as String
Dim sName as String
sInit = vText.Substring(6, 1)
sName = ""
For x as Integer = 8 to vText.Length - 1
if vText.Substring(x) = "," Then Exit For
sName &= vText.Substring(x)
Next
lbl_Output.Text += sName & ", " & sInit
But better you have more than one lbl_Output ...
Something like this should work:
Dim lines As New List(Of String)
For Each s As String In File.ReadAllLines("textfile3.txt")
Dim temp As String = ""
s = s.Substring(s.IndexOf(","c) + 1)
temp = ", " + s.First
s = s.Substring(s.IndexOf(","c) + 1)
temp = s.First + ". " + s.Substring(s.IndexOf(" "c), s.IndexOf(","c) - s.IndexOf(" "c)) + temp
lines.Add(temp)
Next
The list Lines will contain the strings you need.