Vb Flexible Select Case

SwitchStatement for VisualBasic (both VbClassic and VisualBasicDotNet)

[See ElseIfIsSelectCase for languages with stricter limitations on select-case syntax.]

VB's select case is much more flexible if used like this:

Select Case True
  Case <boolean expr 1>
    <block 1>
  Case <boolean expr 2>
    <block 2>
  Case <boolean expr 3>
    <block 3>
  Case True
    <default block>
End Select

In fact this method lets you do range comparisons, call functions, or test several values, just like you wanted.

The original sample from ElseConsideredHelpful rewritten like this becomes:

Private Sub WritePropertyElement(ByVal psName As String, ByVal pvValue As Variant)
   Dim xmlElmt As MSXML.IXMLDOMElement
   ' ...  Code to create the XML Element and write pvValue type information into it.  ...
   Select Case True
   Case IsDate(pvValue)
      xmlElmt.Text = Format$(pvValue, "YYYY/MM/DD HH:NN:SS")
   Case VarType(pvValue) = vbObject
      If pvValue Is Nothing Then
         ' (No text)
      Else
         Call DoObjectSerialization(xmlElmt, pvValue)
      End If
   Case IsNull(pvValue)
      ' (No text)
   Case IsEmpty(pvValue)
      ' (No text)
   Case IsMissing(pvValue)
      xmlElmt.Text = "Missing"
   Case True
      xmlElmt.Text = CStr(pvValue)
   End Select
End Sub

Another actual code sample:

Private Function IsProcedureHeader( aLine As String ) As Boolean
  IsProcedureHeader = True
  Select Case True
   Case BeginsWith(UCase$("private sub"), UCase$(aLine))
   Case BeginsWith(UCase$("public sub"), UCase$(aLine))
   Case BeginsWith(UCase$("friend sub"), UCase$(aLine))
   Case BeginsWith(UCase$("sub"), UCase$(aLine))
   Case BeginsWith(UCase$("private function"), UCase$(aLine))
   Case BeginsWith(UCase$("public function"), UCase$(aLine))
   Case BeginsWith(UCase$("friend function"), UCase$(aLine))
   Case BeginsWith(UCase$("function"), UCase$(aLine))
   Case BeginsWith(UCase$("private property"), UCase$(aLine))
   Case BeginsWith(UCase$("public property"), UCase$(aLine))
   Case BeginsWith(UCase$("friend property"), UCase$(aLine))
   Case BeginsWith(UCase$("property"), UCase$(aLine))
   Case True
     IsProcedureHeader = False
  End Select
End Function

Private Function BeginsWith( aBeginning As String, aText As String ) As Boolean
  BeginsWith = (Left$(aText, Len(aBeginning)) = aBeginning)
End Function

(Good example. I'd probably move "UCase$()" into the "BeginsWith()" or make a new function that does this. -- JeffGrigg)

One can also use direct values instead of expressions.

select case ucase(rs("fmtType"))
  case "T","N","D"    ' text, number, or date
    hout inputBox("text", fldRef, useValue, useWidth, useWidth)
  case "Y"    ' Boolean
    temp = trim(lcase(rs("fldValue")) & "")
    if isBlank(temp) or temp="(either)" then
      useValue = "(either)"
    elseif contains("1,true,yes,on", temp) then
      useValue = "Yes"
    else
      useValue = "No"
    end if
    hout pickList1(fldRef, useValue, "(either),Yes,No")
  case "L"    ' List
    hout pickList1(fldRef, useValue, "(any)," & rs("theList"))
end select

You can do ranges in VB Case . . .

a specific line from a program I am writing at this moment:

Case WM_SETCURSOR, WM_NCHITTEST, WM_MOUSEMOVE, &HA0 To &HA9

selects based on one of three values, or a range.

--NeilEBryant

You can also do...

Select Case expression
    Case Is > 5
        ' Code Here
    ...etc...
End Select

CategoryVisualBasic, CategoryConditionalsAndDispatching