比较三个变量的大小。
比如a(0)=7 a(1)=6 a(2)=7

则n=7

怎么样用一个最简单效率最高的方式得出这样的结果。谢谢。
[解决办法]
function max(x1 as long,x2 as long)as long
if x1>x2 then
max=x1
else
max=x2
end if
end function

调用：

dim mMax as long
mMax=max(max(x1,x2),x3)
[解决办法]

Option Explicit

Private Function MaxItem(ByRef x() As Integer) As Integer
Dim n As Integer, i As Integer
    For i = LBound(x) To UBound(x)
        If x(i) > n Then n = x(i)
    Next i
    MaxItem = n
End Function

Private Sub Command1_Click()
Dim a(2) As Integer

a(0) = 7
a(1) = 6
a(2) = 7

MsgBox MaxItem(a)
End Sub

很显然，你需要遍历所有的元素，且需要记录其中最大者。实际上，不需要两两比较，因为元素很多时会使逻辑很混乱。
[解决办法]
实在是没分可用了

Dim arry(2)
arry(0) = 7
arry(1) = 6
arry(2) = 7

Dim Max As Integer
Max = 0

Dim l
For l = 0 To UBound(arry)
If arry(l) > Max Then
Max = arry(l)
End If
Next

MsgBox "最大数是=" & Max