It would certainly appear that way.
If, rather than a time based seed, you want a randomized seed like OHM's
original example you can update the function as follows.
\\\
Imports System.Security .Cryptography
Imports System.Text
Private Function RandomString(By Val Stringlength As Byte) As String
Dim s As String = _
"0123456789ABCD EFGHIJKLMNOPQRS TUVWXYZabcdefgh ijklmnopqrstuvw xyz"
Dim sb As New StringBuilder
'It's back inside the function but still only gets called once.
Static r As Random = Nothing
If r Is Nothing Then
'4 bytes needed to make an Integer (0 to 3).
Dim seed() As Byte = New Byte(3) {}
Dim rng As New RNGCryptoServic eProvider
'set the byte contents of seed() to random values.
rng.GetBytes(se ed)
'use BitConverter to convert the bytearray to an Integer
r = New Random(BitConve rter.ToInt32(se ed, 0))
End If
Do
sb.Append(s.Cha rs(r.Next(0, 61)))
Loop While sb.Length < Stringlength
Return sb.ToString
End Function
///
"Crirus" <Cr****@datagro up.ro> wrote in message
news:eX******** ******@tk2msftn gp13.phx.gbl...
So Random class is much better than rnd function?
--
Ceers,
Crirus
------------------------------
If work were a good thing, the boss would take it all from you
------------------------------
"Mick Doherty" <md*******@nosp am.ntlworld.com > wrote in message
news:Qa******** *********@newsf ep1-win.server.ntli .net... What's that CInt("0"c)? doesn't work here although Asc("0"c) does, as
does Asc("0").
What's that Machine.Shift.L eft? doesn't work here. I understand what
it's meant to do though.(number between 0 and &HFFFFFFFF).
I like that Random class, hadn't seen that before, but, according to the
documentation, for best performance Random should only be created once.
StringBuilder.A ppend is faster than String +=.
You missed the LCase characters.
My much simpler version of that same function, with default time based
seeding of Random:
Private r As New Random
'I think 255 characters should be enough, although there's no reason
that 'you can't use Integer or Short instead of Byte, and have more.
Private Function RandomString(By Val Stringlength As Byte) As String
Dim s As String = _
"0123456789ABCD EFGHIJKLMNOPQRS TUVWXYZabcdefgh ijklmnopqrstuvw xyz"
Dim sb As New System.Text.Str ingBuilder
Do
sb.Append(s.Cha rs(r.Next(0, 61)))
Loop While sb.Length < Stringlength
Return sb.ToString
End Function
My version generated 100000 * 255character strings in 4 secs as opposed
to yours (updated to use stringbuilder and default seeding for comparison)
taking 6 secs(making the Random object a Class level Private object
reduced this to 5 secs). Without Stringbuilder yours took 23 secs and 21 secs.
Before that Random Class I used the old Rnd function and the fastest I
could get, even using Stringbuilder, was 28 secs.
So I learned something useful Today.
Thankyou
Mick Doherty
"One Handed Man" <Bo****@Duck.ne t> wrote in message
news:bo******** **@titan.btinte rnet.com... Try this - OHM
Public Class StringGenerator
Public Shared Function RandomString(le ngth As Integer) As String
Const zero As Integer = CInt("0"c)
Const nine As Integer = CInt("9"c)
Const capA As Integer = CInt("A"c)
Const capZ As Integer = CInt("Z"c)
Dim guid As Byte() = Guid.NewGuid(). ToByteArray()
Dim seed As Integer = guid(0) + Machine.Shift.L eft(guid(1), 8) +
Machine.Shift.L eft(guid(2), 16) + Machine.Shift.L eft(guid(3), 24)
Dim r As New Random(seed)
Dim s As String = Nothing
Dim i As Integer
For i = 0 To length - 1
Dim n As Integer
Do
n = r.Next(zero, capZ)
Loop While Not(n >= zero And n <= nine Or(n >= capA And n <=
capZ)) s += CChar(n)
Next i
Return s
End Function 'RandomString
End Class 'StringGenerato r
Crirus wrote:
> Is there a function that return some random ID like string
> alphanumeric? Like this:
> A35sDsd1dSGsH
>
> Thanks
> Crirus
