Creating and appending text to txt file in VB NET

Question

Using VB NET  I am trying to create a text file if it doesn t exist or append text to it if exists   For some reason  though it is creating the text file I am getting an error saying process cannot access file   And when I run the program it is writing text  but how can I make it write on a new line   Dim strFile As String    C  ErrorLog    amp  DateTime Today ToString  dd-MMM-yyyy    amp    txt   Dim sw As StreamWriter Dim fs As FileStream   Nothing  If  Not File Exists strFile   Then     Try         fs   File Create strFile          sw   File AppendText strFile          sw WriteLine  Start Error Log for today        Catch ex As Exception         MsgBox  Error Creating Log File       End Try Else     sw   File AppendText strFile      sw WriteLine  Error Message in  Occured at--    amp  DateTime Now       sw Close   End If

User · Answer

While I realize this is an older thread  I noticed the if block above is out of place with using   Following is corrected   Private Sub Button1 Click sender As Object  e As EventArgs  Handles Button1 Click     Dim filePath As String         String Format  C  ErrorLog  0  txt   DateTime Today ToString  dd-MMM-yyyy        Using writer As New StreamWriter filePath  True          If File Exists filePath  Then             writer WriteLine  Error Message in  Occured at--    amp  DateTime Now          Else             writer WriteLine  Start Error Log for today           End If     End Using End Sub

User · Answer

You didn t close the file after creating it  so when you write to it  it s in use by yourself  The Create method opens the file and returns a FileStream object  You either write to the file using the FileStream or close it before writing to it  I would suggest that you use the CreateText method instead in this case  as it returns a StreamWriter    You also forgot to close the StreamWriter in the case where the file didn t exist  so it would most likely still be locked when you would try to write to it the next time  And you forgot to write the error message to the file if it didn t exist   Dim strFile As String    C  ErrorLog    amp  DateTime Today ToString  dd-MMM-yyyy    amp    txt  Dim sw As StreamWriter Try    If  Not File Exists strFile   Then       sw   File CreateText strFile        sw WriteLine  Start Error Log for today      Else       sw   File AppendText strFile     End If    sw WriteLine  Error Message in  Occured at--    amp  DateTime Now     sw Close   Catch ex As IOException    MsgBox  Error writing to log file    End Try   Note  When you catch exceptions  don t catch the base class Exception  catch only the ones that are releveant  In this case it would be the ones inheriting from IOException

User · Answer

Try this   Dim strFile As String    yourfile txt  Dim fileExists As Boolean   File Exists strFile  Using sw As New StreamWriter File Open strFile  FileMode OpenOrCreate       sw WriteLine            IIf fileExists                 Error Message in  Occured at--    amp  DateTime Now                 Start Error Log for today    End Using

User · Answer

This should work for you without changing program logic  by not outputting  Start error  on the top of each file  like the other answers do    Remember to add exception handling code   Dim filePath As String   String Format  C  ErrorLog  0  txt   DateTime Today ToString  dd-MMM-yyyy     Dim fileExists As Boolean   File Exists filePath   Using writer As New StreamWriter filePath  True      If Not fileExists Then         writer WriteLine  Start Error Log for today       End If     writer WriteLine  Error Message in  Occured at--    amp  DateTime Now  End Using

User · Answer

Try it this way   Dim filePath As String      String Format  C  ErrorLog  0  txt   DateTime Today ToString  dd-MMM-yyyy     if File Exists filePath  then  Using writer As New StreamWriter filePath  True  writer WriteLine  Error Message in  Occured at--    amp  DateTime Now   Else writer WriteLine  Start Error Log for today   End Using  end if

User · Answer

Don t check File Exists   like that  In fact  the whole thing is over-complicated  This should do what you need  Dim strFile As String      quot C  ErrorLog  DateTime Today dd-MMM-yyyy  txt quot  File AppendAllText strFile    quot Error Message in  Occured at--  DateTime Now  Environment NewLine  quot    Got it all down to two lines of code

User · Answer

Why not just use the following simple call  with any exception handling added    File AppendAllText strFile   Start Error Log for today      EDITED ANSWER This should answer the question fully   If File Exists strFile    File AppendAllText strFile  String Format  Error Message in  Occured at--  0 dd-MMM-yyyy  1    Date Today  Environment NewLine   Else   File AppendAllText strFile   Start Error Log for today 0 Error Message in  Occured at--  1 dd-MMM-yyyy  0    Environment NewLine  Date Today  End If

[vb.net] Creating and appending text to txt file in VB.NET

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