How to Create a Temp File with a Specific Extension with .Net

How can I create a temp file with a specific extension with .NET?

Guaranteed to be (statistically) unique:

string fileName = System.IO.Path.GetTempPath() + Guid.NewGuid().ToString() + ".csv"; 

(To quote from the wiki article on the probabilty of a collision:

...one's annual risk of being hit by a
meteorite is estimated to be one
chance in 17 billion [19], that means
the probability is about 0.00000000006
(6 × 10−11), equivalent to the odds of
creating a few tens of trillions of
UUIDs in a year and having one
duplicate. In other words, only after
generating 1 billion UUIDs every
second for the next 100 years, the
probability of creating just one
duplicate would be about 50%. The
probability of one duplicate would be
about 50% if every person on earth
owns 600 million UUIDs

EDIT: Please also see JaredPar's comments.

Generate a unique temporary file name with a given extension using .NET

Please See: How can I create a temp file with a specific extension with .net ?

How do I create a temp file in a directory other than temp?

Path.Combine(directoryYouWantTheRandomFile, Path.GetRandomFileName())

Is there a way to execute an exe stored with a temp file name?

I think it is possible.. set the Process.StartInfo.UseShellExecute property to False prior to starting the process, e.g.:

 System.Diagnostics.Process p = new System.Diagnostics.Process();
 p.StartInfo.FileName = @"c:\tmp\a123.tmp";
 p.StartInfo.UseShellExecute  = false;
 p.Start();

This will start the process directly and the file should be considered to be executable itself. Does it work for you?

Writing temp files

You should be able to do this without creating a temporary file.

Just create $img like:

$img = [System.Drawing.Image]::FromStream([System.IO.MemoryStream]::new($User.thumbnailPhoto))
$pictureBox.Width  = $img.Width
$pictureBox.Height = $img.Height
$pictureBox.Image  = $img

^{Don't forget to remove the form from memory after closing with $form.Dispose()}

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If you insist on using a temporary file, then be aware that the $img object keeps a reference to the file untill it is disposed of.

Something like:

# get a temporary file name
$Filename = [System.IO.Path]::GetTempFileName()
[System.IO.File]::WriteAllBytes($Filename, $User.thumbnailPhoto)

# get an Image object using the data from the temporary file
$img = [System.Drawing.Image]::FromFile($Filename)

$pictureBox.Width  = $img.Width
$pictureBox.Height = $img.Height
$pictureBox.Image  = $img

$form.Controls.Add($pictureBox)
$form.ShowDialog()

# here, when all is done and the form is no longer needed, you can
# get rid of the $img object that still has a reference to the
# temporary file and then delete that file.
$img.Dispose()
Remove-Item $Filename

# clean up the form aswell
$form.Dispose()

How to handle properly temporary files?

Once you write something on the disk you can't be 100% that you will able to delete it. Moreover, even if you delete the file, you can't be sure that file can't be recovered.

So you have to ask why I need to delete the file. If it contains some secret, keep it in memory. If you can't fit the file into memory, write it encrypted on the disk and keep only key in the memory.

If you relax 100% to 99%, I would go for creating a file with Path.GetTempFileName and deleting it in finally block.

If 99% is not enough but 99.98% is, I would store names of created temporary files in persistent storage and regularly check if they are deleted.

How can I associate a specific file extension with my application?

Read Hans Passant comment.
Using direclty Setup Deployment Project and defining there file associations is quick and easy. Perfect.

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