HOWTO: Simulate Visual Basic 6.0 String Functions in VB5

• Microsoft Visual Basic Learning, Professional, and Enterprise Editions for Windows, versions 5.0, 6.0
• Microsoft Visual Basic Standard, Professional, and Enterprise Editions for Windows, version 4.0

SUMMARY

Visual Basic version 6.0 introduces a number of new string functions to simplify string manipulation in your code. This article describes how the same functionality can be used with earlier versions of Visual Basic.

MORE INFORMATION

The following additional string functions are present in Visual Basic 6.0:

Function      Description
--------      -----------
Join          Used to join arrays elements.

Split         Split a string into a variant array.

InStrRev      Similar to InStr but searches from end of string.

Replace       To find a particular string and replace it.

Reverse       To reverse a string. 

1. Start a new project. Form1 is created by default.



2. Add a new module to the project and add the following code to the module:

   
         Option Explicit
   
         Public Function Join(source() As String, Optional _
               sDelim As String = " ") As String
         Dim sOut As String, iC As Integer
         On Error GoTo errh:
             For iC = LBound(source) To UBound(source) - 1
                 sOut = sOut & source(iC) & sDelim
             Next
             sOut = sOut & source(iC)
             Join = sOut
             Exit Function
         errh:
             Err.Raise Err.Number
         End Function
   
         Public Function Split(ByVal sIn As String, Optional sDelim As _
               String, Optional nLimit As Long = -1, Optional bCompare As _
                VbCompareMethod = vbBinaryCompare) As Variant
             Dim sRead As String, sOut() As String, nC As Integer
             If sDelim = "" Then
                 Split = sIn
             End If
             sRead = ReadUntil(sIn, sDelim, bCompare)
             Do
                 ReDim Preserve sOut(nC)
                 sOut(nC) = sRead
                 nC = nC + 1
                 If nLimit <> -1 And nC >= nLimit Then Exit Do
                 sRead = ReadUntil(sIn, sDelim)
             Loop While sRead <> ""
             ReDim Preserve sOut(nC)
             sOut(nC) = sIn
             Split = sOut
         End Function
   
         Public Function ReadUntil(ByRef sIn As String, _
               sDelim As String, Optional bCompare As VbCompareMethod _
             = vbBinaryCompare) As String
             Dim nPos As String
             nPos = InStr(1, sIn, sDelim, bCompare)
             If nPos > 0 Then
                 ReadUntil = Left(sIn, nPos - 1)
                 sIn = Mid(sIn, nPos + Len(sDelim))
             End If
         End Function
   
         Public Function StrReverse(ByVal sIn As String) As String
             Dim nC As Integer, sOut As String
             For nC = Len(sIn) To 1 Step -1
             sOut = sOut & Mid(sIn, nC, 1)
             Next
             StrReverse = sOut
         End Function
   
         Public Function InStrRev(ByVal sIn As String, sFind As String, _
          Optional nStart As Long = 1, Optional bCompare As _
               VbCompareMethod = vbBinaryCompare) As Long
             Dim nPos As Long
             sIn = StrReverse(sIn)
             sFind = StrReverse(sFind)
             nPos = InStr(nStart, sIn, sFind, bCompare)
             If nPos = 0 Then
                 InStrRev = 0
             Else
                 InStrRev = Len(sIn) - nPos - Len(sFind) + 2
             End If
         End Function
   
         Public Function Replace(sIn As String, sFind As String, _
               sReplace As String, Optional nStart As Long = 1, _
               Optional nCount As Long = -1, Optional bCompare As _
               VbCompareMethod = vbBinaryCompare) As String
   
             Dim nC As Long, nPos As Integer, sOut As String
             sOut = sIn
             nPos = InStr(nStart, sOut, sFind, bCompare)
             If nPos = 0 Then GoTo EndFn:
             Do
                 nC = nC + 1
                 sOut = Left(sOut, nPos - 1) & sReplace & _
                    Mid(sOut, nPos + Len(sFind))
                 If nCount <> -1 And nC >= nCount Then Exit Do
                 nPos = InStr(nStart, sOut, sFind, bCompare)
             Loop While nPos > 0
         EndFn:
             Replace = sOut
         End Function
    




3. Add two CommandButtons to Form1. Add the following code to the General Declaration section of Form1:

   
         Option Explicit
   
         Dim MyArray(2) As String, MyStr As String, MyVar As Variant
   
         Private Sub Command1_Click()
             MyArray(0) = "item1"
             MyArray(1) = "item2"
             MyArray(2) = "item3"
             MyStr = Join(MyArray, ";")
             Debug.Print MyStr
         End Sub
   
         Private Sub Command2_Click()
             Dim i As Integer
             MyVar = Split(MyStr, ";")
             For i = LBound(MyVar) To UBound(MyVar)
             Debug.Print MyVar(i)
             Next
         End Sub
   
         Private Sub Form_Load()
             Command1.Caption = "Join"
             Command2.Caption = "Split"
         End Sub
    




4. Press the F5 key to run the project. Click on Join, and note in the debug window that the array elements are joined. Click on Split to split a string into a variant array.



5. Pause the project by pressing the CTRL+BREAK key combination or clicking the Pause button on the toolbar. Test the remaining functions by typing the following lines in the immediate window and verifying the results:

   ?instrrev("//drive/dir","/")
   8
   
   ?strreverse("input string")
   gnirts tupni
   
   ?replace("input string"," ", "-",4,1)
   input-string

   NOTE: The errors generated may not exactly coincide with those generated by the Visual Basic 6.0 intrinsic string functions.

Additional query words: kbDSupport kbDSD beta99 kbVBp kbVBp400 kbVBp500 kbVBp600 kbVBA

Keywords : kbGrpVB
Version :
Platform : WINDOWS
Issue type : kbhowto