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Using a text in a textbox for a file name?

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Join Date: May 2009

Posts: 40

Reputation: lolwtf is an unknown quantity at this point

Solved Threads: 0

lolwtf

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Using a text in a textbox for a file name?

May 20th, 2009

I working on a personal project of mine and got stuck. The program is a simple quiz in which the user answers some questions, and their results are saved into a text file. Reading and writing to text files is easy so I don't need help with that. On my form I have a textbox and two buttons. The user will input his/her name into the textbox and hit a "take quiz" button. That button will create a text file, but i want the text files name to be what the user just entered in the textbox. The idea is that for my second button "Load File" will pull up the text file under their name. Any help would be appreciated.

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Join Date: Aug 2008

Posts: 710

Reputation: Teme64 will become famous soon enough

Solved Threads: 114

Teme64

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Re: Using a text in a textbox for a file name?

May 20th, 2009

The only problem is to validate user input as a valid file name. AFAIK the following should be 100% bullet-proof method

 Help with Code Tags 
 VB.NET Syntax (Toggle Plain Text) 
Dim FileName As String
Dim bIsValidFileName As Boolean
Dim i As Integer
 
' Get user input
FileName = TextBox1.Text
' Validate
bIsValidFileName = True
' Can't be empty
If String.IsNullOrEmpty(FileName) Then
  bIsValidFileName = False
End If
' Check invalid characters
For i = 0 To Path.GetInvalidFileNameChars.GetUpperBound(0)
  If FileName.IndexOf(Path.GetInvalidFileNameChars(i)) >= 0 Then
    ' Illegal character
    bIsValidFileName = False
    Exit For
  End If
Next i
' Save or reprompt input
If bIsValidFileName Then
  ' Save the file
Else
  MessageBox.Show("'" & FileName & "' is not a valid filename", "Filename", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
End If
Dim FileName As String
Dim bIsValidFileName As Boolean
Dim i As Integer

' Get user input
FileName = TextBox1.Text
' Validate
bIsValidFileName = True
' Can't be empty
If String.IsNullOrEmpty(FileName) Then
  bIsValidFileName = False
End If
' Check invalid characters
For i = 0 To Path.GetInvalidFileNameChars.GetUpperBound(0)
  If FileName.IndexOf(Path.GetInvalidFileNameChars(i)) >= 0 Then
    ' Illegal character
    bIsValidFileName = False
    Exit For
  End If
Next i
' Save or reprompt input
If bIsValidFileName Then
  ' Save the file
Else
  MessageBox.Show("'" & FileName & "' is not a valid filename", "Filename", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
End If

Instead of flagging bad characters in the for loop you could also simply remove them

 Help with Code Tags 
 VB.NET Syntax (Toggle Plain Text) 
' Check invalid characters
For i = 0 To Path.GetInvalidFileNameChars.GetUpperBound(0)
  If FileName.IndexOf(Path.GetInvalidFileNameChars(i)) >= 0 Then
    ' Remove illegal character
    FileName.Replace(Path.GetInvalidFileNameChars(i), "")
  End If
Next i
' Now you have to check that you don't end up with an empty string after replacing characters
If String.IsNullOrEmpty(FileName) Then
  bIsValidFileName = False
End If
' Check invalid characters
For i = 0 To Path.GetInvalidFileNameChars.GetUpperBound(0)
  If FileName.IndexOf(Path.GetInvalidFileNameChars(i)) >= 0 Then
    ' Remove illegal character
    FileName.Replace(Path.GetInvalidFileNameChars(i), "")
  End If
Next i
' Now you have to check that you don't end up with an empty string after replacing characters
If String.IsNullOrEmpty(FileName) Then
  bIsValidFileName = False
End If

I suggest putting the code above in a function which returns the file name so you can call it both before saving and loading the file.