感觉重复率好像有点高。
Imports System.Text
Module Module1
Sub Main()
Dim rnd1 As New Random
Dim builder As New StringBuilder()
Dim passWord As String = Nothing
Dim ctr As Integer
Dim possiblePassword As String = "qwertyuiopkjhgfdsazxcvbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!@#$%^&*(),.?"
possiblePassword.ToCharArray()
Dim c As Integer = Len(possiblePassword)
For i = 1 To 10
ctr = rnd1.Next(0, c)
passWord = possiblePassword(ctr)
Console.Write(passWord)
Next
Console.ReadLine()
End Sub
End Module

请问你builder定义来干哈的？围观？

另外，你是要生成10个字符串长度的密码还是一个字符串长度的密码？

Public Class Form1
Dim rnd1 As New Random
Dim builder As New Text.StringBuilder()
Dim ctr As Byte
Dim passwordLength As Byte = 16
Dim passWord As String = Nothing
Dim possiblePassword As String = "qwertyuiopkjhgfdsazxcvbnm1234567890QWERTYUOPLKJHGFDSAZXCVBNM!@#$%^&*(),.?"
Dim c As Byte = Len(possiblePassword)
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
possiblePassword.ToCharArray()
RadioButton2.Checked = True
Label1.Text = getPassword()
Clipboard.SetText(Label1.Text)
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
If RadioButton1.Checked = True Then
passwordLength = 10
End If
Label1.Text = getPassword()
Clipboard.SetText(Label1.Text)
End Sub
Function getPassword() As String
builder.Clear()
Randomize()
For i = 1 To passwordLength
ctr = rnd1.Next(0, c)
passWord = possiblePassword(ctr)
builder.Append(passWord)
Next
Return builder.ToString
End Function
End Class

搞定：
Public Class Form1
Dim rnd1 As New Random
Dim builder As New Text.StringBuilder()
Dim ctr As Byte
Dim passwordLength As Byte = 16
Dim passWord As String = Nothing
Dim possiblePassword As String = "qwertyuiopkjhgfdsazxcvbnm1234567890QWERTYUOPLKJHGFDSAZXCVBNM!@#$%^&*(),.?"
Dim c As Byte = Len(possiblePassword)
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
possiblePassword.ToCharArray()
RadioButton2.Checked = True
Label1.Text = getPassword()
Clipboard.SetText(Label1.Text)
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
If RadioButton1.Checked = True Then
passwordLength = 10
Else
passwordLength = 16 ' 增加这一句就好了
End If
Label1.Text = getPassword()
Clipboard.SetText(Label1.Text)
End Sub
Function getPassword() As String
builder.Clear()
Randomize()
For i = 1 To passwordLength
ctr = rnd1.Next(0, c)
passWord = possiblePassword(ctr)
builder.Append(passWord)
Next
Return builder.ToString
End Function
End Class