Asc > ?

[ADO DOT NET]

Hi,

I want to convert this function to VB.NET:

Private Function FilterFileName(ByVal FileName As String) As String
  FilterFileName = Empty
  Dim MyLoop As Integer
  For MyLoop = 1 To Len(FileName)
   If Asc(Mid$(FileName, MyLoop, 1)) >= 97 And Asc(Mid$(FileName, MyLoop, 1)) <= 122 Or _
      Asc(Mid$(FileName, MyLoop, 1)) >= 65 And Asc(Mid$(FileName, MyLoop, 1)) <= 90 Or _
      Asc(Mid$(FileName, MyLoop, 1)) >= 48 And Asc(Mid$(FileName, MyLoop, 1)) <= 57 Or _
      Asc(Mid$(FileName, MyLoop, 1)) = 32 Or _
      Asc(Mid$(FileName, MyLoop, 1)) = 45 Or _
      Asc(Mid$(FileName, MyLoop, 1)) = 95 Then
       FilterFileName = FilterFileName & Mid$(FileName, MyLoop, 1)
   End If
  Next
End Function

Everything is alright, I just cannot find the new Asc() method in .NET.

Each old method has a .NET version, for example InStr instead of Mid$ but where is new method for ASC()?

Thanks.

[PlausiblyDamp]

You could just use Convert.ToInt32 on the character. Out of interest what is the code attempting to do?

[snarfblam]

Instead of the Mid() function, you can use the String.Chars property to get an individual character. Its quicker and returns a Char value, which you can compare with > and < without using the Asc() method.

Private Function FilterFileName(ByVal FileName As String) As String
  FilterFileName = Empty
  Dim MyLoop As Integer
  For MyLoop = 1 To Len(FileName)
   If FileName.Chars(MyLoop) >= "a"c And FileName.Chars(MyLoop) <= "z"c Or _
      FileName.Chars(MyLoop) >= "A"c And FileName.Chars(MyLoop) <= "Z"c Or _
      FileName.Chars(MyLoop) >= "0"c And FileName.Chars(MyLoop) <= "9"c Or _
      FileName.Chars(MyLoop) = " "c Or _
      FileName.Chars(MyLoop) = "-"c Or _
      FileName.Chars(MyLoop) = "_"c Then
       FilterFileName &= FileName.Chars(MyLoop)
   End If
  Next
End Function

You could make it even simpler, too, by using the functions of the Char type.

[Vb]

Private Function FilterFileName(ByVal FileName As String) As String

FilterFileName = Empty

Dim MyLoop As Integer

For MyLoop = 1 To Len(FileName)

Dim C As Char = FileName.Chars(MyLoop)

If Char.IsLetterOrDigit© Or _

C = " "c Or _

C = "-"c Or _

C = "_"c Then

FilterFileName &= FileName.Chars(MyLoop)

End If

Next

End Function[/code]

The System.IO.Path class has some functions that might make things simpler for you, too.

[Nate Bross]

You might also use RegEx

 

Imports System.Text.RegularExpressions;

Dim pattern as String = "^[a-zA-Z0-9_\s-]+$"
Dim expression as Regex = new Regex(pattern)

If expression.IsMatch(YourInputVariable) = True Then
   ' Valid file name
Else
   'Bad file name
End If

 

This will provide you with a more controlled file name than System.IO.Path methods will give you.