Private Sub Command1_Click()
Dim i As Integer
Dim sOld As String, sReverse As String

sOld = "123"

For i = Len(sOld) To 0 Step -1
   If i > 0 Then
     sReverse = sReverse & Mid(sOld, i, 1)
   End If
Next
Text1 = sReverse
End Sub

: Private Sub Command1_Click()
: Dim i As Integer
: Dim sOld As String, sReverse As String
: 
: sOld = "123"
: 
: For i = Len(sOld) To 0 Step -1
:    If i > 0 Then
:      sReverse = sReverse & Mid(sOld, i, 1)
:    End If
: Next
: Text1 = sReverse
: End Sub
: 

Private Function Mod_sReverse(ByRef sOriginal As String) As String

Dim lIndex As Long
Dim lLen As Long
Dim sReverse As String

lLen = Len(sOriginal)
'''Preallocate string
sReverse = sOriginal
For lIndex = 1 To lLen
   '''move each character
   Mid$(sReverse, (lLen - lIndex + 1), 1) = Mid(sOriginal, lIndex, 1)
Next lIndex
Mod_sReverse = sReverse
End Function

Dim sString As String
Dim sReverse As String

sString = "123"
sReverse = StrReverse(sString)

: Dim sString As String
: Dim sReverse As String
: 
: sString = "123"
: sReverse = StrReverse(sString)
: