在VBA Excel中为多个单元格使用udf

Question

a user defined function I use in excel

Function Hex2RGB(hex As String) As String

    Red = Val("&H" & Mid(hex, 1, 2))
    Green = Val("&H" & Mid(hex, 3, 2))
    Blue = Val("&H" & Mid(hex, 5, 2))

  Debug.Print RGB(Red, Green, Blue)
    Hex2RGB = RGB(Red, Green, Blue)

End Function

I have a worksheet with a 10 times 10 matrix for which this function would need to be used for every cell in the range. There has to be some way that I don't have to click on each cell and enter =Hex2RGB("value") manually? when I write value I am referring to something like OD62A2....which is the colour than to be transformed in excel format

Answer 1

Use a range parameter instead of value as below. Set the function manually to the first cell (eg left upper cell in the matrix) then copy and paste it across the matrix - the range will change

Public Function Hex2RGB(r As Range) As String
    Dim hex As String: r.Value
    Red = Val("&H" & Mid(hex, 1, 2))
    Green = Val("&H" & Mid(hex, 3, 2))
    Blue = Val("&H" & Mid(hex, 5, 2))

  Debug.Print RGB(Red, Green, Blue)
    Hex2RGB = RGB(Red, Green, Blue)

End Function

Answer 2

Step 1: Add the following macro. This macro will iterate over the cells in the selected range, and replace them with a formula based on its own value, which I think is what you are trying to do.

Sub GetHexValues()
    Dim rng as Range
    Dim cl as Range
    Set rng = Range(Selection.Address)
    For each cl in rng.Cells
        cl.Formula = "=Hex2RGB(" & Chr(34) & cl.Value & Chr(34) & ")"
    Next
End Sub

Step 2 Make sure your function is:

Public Function Hex2RGB(hex) As String
    Red = Val("&H" & Mid(hex, 1, 2))
    Green = Val("&H" & Mid(hex, 3, 2))
    Blue = Val("&H" & Mid(hex, 5, 2))

    Debug.Print RGB(Red, Green, Blue)
    Hex2RGB = RGB(Red, Green, Blue)

End Function

Step 3: Select the matrix range. (NB: Normally I recommend not using Select but as a means of user-input it is OK to do that here, I think.)

There is generally speaking, no way to use a UDF worksheet function to manipulate a range of cells in the manner you're describing. UDF's can generally not alter many properties and values of cells/ranges except the cell that is calling the function. This is to avoid circular reference/etc. (there are workarounds to this limitation, but generally accepted rule is to use Subroutines to manipulate the worksheet objects).