VB.NET，这个程序是啥意思啊？

ByVal iTotal As Integer) As Single
8 'Calculation successful".Click
2 Dim sngAvg As Single
3 sngAvg = GetAverage(01 Private Sub FirstTryCatchButton_Click(ByVal sender As System; This only executes if the line above generated no error
17 MessageBox.Object; iItems)
15
16 ' If the calculation failed.EventArgs) Handles FirstTryCatchButton; Code that might throw an exception is wrapped in a Try block
9 Try
10 Dim sngAverage As Single
11
12 ', you get here
22 MessageBox.Show("Calculation unsuccessful - exception caught", 100)
4
5 End Sub
6
7 Private Function GetAverage(ByVal iItems As Integer; This will cause an exception to be thrown if iItems
13 = 0
14 sngAverage = CSng(iTotal \.Show(")
18 Return sngAverage
19
20 Catch excGeneric As Exception
21 ', ByVal e As System

FirstTryCatchButton
将某个按钮name改成这个。
功能，大概是测试try catch==

dim n as integer         dim a(19) as string, i%, j%, k$         i = 0         label1.text = ""         randomize()         for i = 0 to 19             k = ""             n = int(rnd() * 9 + 1)             for j = 1 to n                 k &= chr(int(rnd() * 26 + 97))             next j             a(i) = k         next i         for i = 0 to 19             label1.text &= a(i) & space(5)             if (i + 1) mod 5 = 0 then                 label1.text &= vbcrlf             end if         next i 这是我改了你的代码做成的，看一下是不是符合要求