那我应该怎么改？说清楚点。我新手

建议你最好将运算写成函数：
private function Add (Num1 as double,Num2 as doule,optional CalculatePression as integer = 16) as doublie
   if ismissing(CalculatePression)=true then
      add=num1+num2

   else
      add=math.round(num1+num2,CalculatePression)

   endif

end function
其它的一次类推减、乘、除等计算函数。
在
private sub Command_Click()
Dim Number1 As double
dim Number2 As double

   Number1 = Val(InputText1)
   Number2 = Val(InputText2)
   OutputText.Text = add(Number1,Number2)

end sub
没必要AddOption=true的判断。我觉得奇怪的是，当主功能调通后，你再根据需要再加上其它附加的东西。就像上面有人说得一样，你就没给AddOption进行赋值AddOption=true，它怎么可能去进行加法计算？所以，我怀疑你的这段代码不是你编的。

简单代码
Private Sub Command1_Click()
Dim number1 As Single, number2 As Single, sum As Single
number1 = Val(Text1.Text)
number2 = Val(Text2.Text)
sum = number1 + number2
Text3.Text = sum
End Sub

[[it] 本帖最后由 swz 于 2008-6-29 22:43 编辑 [/it]]