Visual Basic: i have a file containg usernames and passwords but i want to read them back in so the user can log back in - vb.net

Question

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.

Answer 1

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

Answer 2

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.