Random String generator throwing out duplicates issue

[JumboCactuar]

Hi,
i'm using this code to generate a unique 4 character string, but hours later i'm seeing it generate the same 4 character strings again

Am i doing something wrong?

Function GenerateRandomString() As String
    Dim i As Integer
    Dim strResult As String
    Dim strChars As String
    strChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ123456789"

    ' Initialize the random-number generator.
    Randomize

    For i = 1 To 4
        strResult = strResult & Mid(strChars, Int((Len(strChars) * Rnd) + 1), 1)
    Next i

    GenerateRandomString = strResult
End Function

 

[6StringJazzer]

This raises the question of how the function is called. Is OP calling it as a UDF from a cell, or calling it from other code?

 

[JumboCactuar]

Hi
Thanks for all the info

I am calling the function from a button which basically uses

Private Sub CommandButton1_Click()

    Dim randomString As String
    
    randomString = GenerateRandomString()
    
    aFilename  = Format(Date, "YYYYMMDD") & randomString
    
    'Code to save file below
    
End Sub

So as per suggestions above, i shoam better calling Ramdomize under a Workbook_Open sub ?

 

[6StringJazzer]

Yes. Call Randomize under Workbook_Open. Its duration will be the entire VBA session, until you close the workbook, or reset VBA (such as ending execution after an error is raised, or pressing the "Reset" button on the VBA IDE toolbar).