Help with random in a url.

[zarko33]

Hello vb forums this is my first post here,
So,I am trying to make a program that gets random images from http://prntscr.com/.
My main concept is:
you click the random button and it will generate a random string of 5 numbers/lowercase letters that will be added after http://prntscr.com/ like http://prntscr.com/58whco and then the image will show up in the web browser.

the code I have now:

Public Class Form1

    Public Function RandomString(ByVal length As Integer) As String
        Dim sb As New System.Text.StringBuilder
        Dim chars() As String = {"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", _
               "1", "2", "3", "4", "5", "6", "7", "8", "9", "0"}
        Dim upperBound As Integer = UBound(chars)

        For x As Integer = 5 To length
            sb.Append(chars(Int(Rnd() * upperBound)))
        Next

        Return sb.ToString

    End Function


    Private Sub FButton2_Click(sender As Object, e As EventArgs) Handles FButton2.Click

    End Sub

    Private Sub FButton1_Click(sender As Object, e As EventArgs) Handles FButton1.Click


    End Sub

    Private Sub CheckBox1_CheckedChanged(sender As Object, e As EventArgs) Handles CheckBox1.CheckedChanged

        Me.Close()

    End Sub
End Class

Thanks in advance.

[zarko33]

Just found that:

Public Function CheckURL(ByVal urltocheck As String)
        Dim url As New System.Uri("http://" & urltocheck)
        Dim req As System.Net.WebRequest
        req = System.Net.WebRequest.Create(url)
        Dim resp As System.Net.WebResponse
        Try
            resp = req.GetResponse()
            resp.Close()
            req = Nothing
            Return True
        Catch ex As Exception
            req = Nothing
            Return False
        End Try
    End Function

in the code bank maybe I can add it to check if the url exist to make it so it will skip unused urls?

[Shaggy Hiker]

Yeah, you might as well. You should also stop using Rnd in favor of the Random object that was introduced in .NET.

[ShadowTzu]

I agree with previous comment and I add just a little update:

Private mRandom As New Random
Private mchars As String = "abcdefghijklmnopqrstuvwxyz1234567890"
Public Function RandomString(ByVal length As Integer) As String
Dim sb As New System.Text.StringBuilder
For x As Integer = 0 To Math.Max(4, length - 1)
    sb.Append(mchars(mRandom.Next(mchars.Length)))
Next

Return sb.ToString
End Function