Excel's Formula - sisman

702
Part VI: Developing Custom Worksheet Functions
Function REVERSETEXT(text As String) As String
‘ Returns its argument, reversed
REVERSETEXT = StrReverse(text)
End Function
This function reverses the contents of its single-cell argument (which can be text or a value). If
the argument is a multicell range, the function returns #VALUE!
Assume that you want this function to work only with strings. If the argument does not contain a
string, you want the function to return an error value (#N/A). You may be tempted to simply
assign a string that looks like an Excel formula error value. For example:
REVERSETEXT = “#N/A”
Although the string looks like an error value, it is not treated as such by other formulas that may
reference it. To return a real error value from a function, use the VBA CVErr function, which converts
an error number to a real error.
Fortunately, VBA has built-in constants for the errors that you want to return from a custom
function. These constants are listed here:
xlErrDiv0
xlErrNA
xlErrName
xlErrNull
xlErrNum
xlErrRef
xlErrValue
The following is the revised REVERSETEXT function:
Function REVERSETEXT(text As Variant) As Variant
‘ Returns its argument, reversed
If WorksheetFunction.ISNONTEXT(text) Then
REVERSETEXT = CVErr(xlErrNA)
Else
REVERSETEXT = StrReverse(text)
End If
End Function