Private Sub Command1_Click()
Dim a As Double, b As Integer, r As Single, n As Integer
n = 0
r = 0.01
a = 12
Do While a >= 20
a = a * (1 + r)
n = n + 1
Loop
Print n
End Sub

这是个很简单的例子，计算N，为什么我的N老为0

看看do...loop的帮助吧。

因为你的a = 12啊

循环条件不成立  无法进入循环

你这个东西我实在没能理解，你自己写的吗?

因为 a =12 ,不满足循环条件，所以跳过循环语句，直接输出结果。

Private Sub Command1_Click()
Dim a As Double, b As Integer, r As Single, n As Integer
n = 0
r = 0.01
a = 12
Do While a 〈 20
a = a * (1 + r)
n = n + 1
Loop
Print n
End Sub
改成这样就可以执行了！！

跟我一样，确实是菜鸟。还要继续努力呀。