如何調用只傳遞一個可選參數的函數？

Question

如果我的函數看起來像

function(optional byval string1 as String,optional byval string2 as String,optional byval string3 as String) 

，我只想要調用由進入細胞"=function(string3)"提供string3的功能，我該怎麼辦呢？

Answer 1

這有可能在以下兩種方式之一...

1. 調用程序，並確定由 「跳躍」 unusued PARMS其可選參數被用於：

Function MyFunc(optional a as integer, _ 
       optional b as integer, _ 
       optional c as integer) as double 
    MyFunc = c * 3.14159 
End Function 

=MyFunc(,,12) <== called as UDF on worksheet or in VBA module 

使用參數列表編碼您的函數：

Function MyFunc(args() As Variant) As Double 
    Dim numberOfArgs As Integer 
    Dim arg As Variant 
    Dim i As Integer 
    Dim answer As Double 
    numberOfArgs = UBound(args) 
    i = 1 
    For Each arg In args 
     Debug.Print "arg(" & i & ") = " & arg 
     answer = Int(arg) * 3.14159 
     i = i + 1 
    Next arg 
    MyFunc = answer 
End Function 

Sub test1() 
    Dim parms() As Variant 
    ReDim parms(1 To 3) 
    'parms(1) = ?? 
    'parms(2) = ?? 
    parms(3) = 21 
    Debug.Print MyFunc(parms) 
End Sub