How to create unique file name?

Question

I copy image files from one folder to another with help of File.Copy() method.

I need to give unique file name to the copied image file before it is pasted to the folder.

Any idea how I can implement this?

See: http://stackoverflow.com/questions/1602578/c-what-is-the-fastest-way-to-generate-a-unique-filename — Emond, Jul 29 '12 at 08:46
I don't think that's an exact duplicate, because it asks for the *fastest* way, which probably isn't the best, most simple and maintainable way. — Anders Abel, Jul 29 '12 at 08:57

score 5 · Accepted Answer · answered Jul 29 '12 at 08:48

5

You can use Path.GetTempFileName

more info at: http://msdn.microsoft.com/en-us/library/system.io.path.gettempfilename(v=vs.100).aspx

a quote from the link:

"Creates a uniquely named, zero-byte temporary file on disk and returns the full path of that file."

answered Jul 29 '12 at 08:48

eyossi

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This would be good for creating a temp file to write temp data in to. It is not ideal for simply generating a unique name. – HackSlash Jul 09 '18 at 22:28
@HackSlash correct. My answer is not the correct one since the file can be deleted as it is a temporary file. (Upvoted the better answers below) – eyossi Aug 06 '18 at 18:30

score 5 · Answer 2 · edited Jul 21 '14 at 23:07

5

Eyossi's answer should be the accepted solution but another alternative:-

You could use a guid to create a unique name ("Such an identifier has a very low probability of being duplicated."):

Dim filename As String = Guid.NewGuid().ToString + ".png"

edited Jul 21 '14 at 23:07

winwaed

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answered Jul 29 '12 at 08:54

Matt Wilko

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Sorry - I was working in C#. I think my brain must have automatically removed the Dim *** As String :-) – winwaed Jul 22 '14 at 12:28
A GUID was not designed for this purpose where `Path.GetRandomFileName()` was. The result is a similarly incomprehensible string. – HackSlash Jul 09 '18 at 22:27

ivanwong888899999 · Answer 3 · 2012-07-30T17:12:36.243

4

Here's another way to do it

fileName = User_Appended_File_Name & "_" & DateTime.Now.ToString("yyyyMMdd_HH_mm_ss")

It would create a fairly identifiable File Name, with the added advantage of knowing when it was created, a big ol' timestamp.

edit: It will not work if the file saving rate is faster than 1second.

edited Jul 30 '12 at 17:12

answered Jul 30 '12 at 16:30

ivanwong888899999

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This fails completely if two files are created in the same second, which could happen quite frequently. – Andrew Barber Jul 30 '12 at 17:00
^ agreed but for scenario's that take longer than a second (ie exporting to excel file format on a local PC) this works well. Plus you can sort the files in the folder grouped by file type. – Jeremy Thompson Mar 26 '19 at 00:08

score 3 · Answer 4 · answered Jul 09 '18 at 22:24

I recommend using Path.GetRandomFileName().

The previously accepted answer was to use Path.GetTempFileName which creates a file. This is not ideal when that file is going to be the target of a file copy operation, as stated in the question.

Unlike GetTempFileName, GetRandomFileName does not create a file. When the security of your file system is paramount, this method should be used instead of GetTempFileName.

SOURCE: https://msdn.microsoft.com/en-us/library/system.io.path.getrandomfilename(v=vs.110).aspx

EXAMPLE:

Imports System.IO

Module Module1

    Sub Main()
        Dim fileName = Path.GetRandomFileName()
        Console.WriteLine("Random file name is " & fileName)
    End Sub

End Module

' This code produces output similar to the following:   
' Random file name is w143kxnu.idj

score 0 · Answer 5 · answered Jul 29 '12 at 08:45

0

You may use current date-time as the file name.

answered Jul 29 '12 at 08:45

Krishanu Dey

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You should note that this would fail if two files are created during the same second, or whatever the smallest time increment indicated by the timestamp is. – Andrew Barber Jul 30 '12 at 17:01

How to create unique file name?

5 Answers5