res = arr(LBound(arr))
For i = LBound(arr) 1 To UBound(arr)
If arr(i) > res Then res = arr(i)
Next
Max = res
End Function
去掉res变量，使用函数名称本身这个局部变量，可以使程序更加简练：
Function Max(arr() As Long) As Long
Dim i As Long
Max = arr(LBound(arr))
For i = LBound(arr) 1 To UBound(arr)
If arr(i) > Max Then Max = arr(i)
Next
End Function