How to make a valid Windows filename from an arbitrary string?

c# windows filenames
Ken picture Ken · Mar 6, 2009 · Viewed 40.5k times · Source

I've got a string like "Foo: Bar" that I want to use as a filename, but on Windows the ":" char isn't allowed in a filename.

Is there a method that will turn "Foo: Bar" into something like "Foo- Bar"?

Answer

Diego Jancic picture Diego Jancic · Mar 6, 2009

Try something like this:

string fileName = "something";
foreach (char c in System.IO.Path.GetInvalidFileNameChars())
{
   fileName = fileName.Replace(c, '_');
}

Edit:

Since GetInvalidFileNameChars() will return 10 or 15 chars, it's better to use a StringBuilder instead of a simple string; the original version will take longer and consume more memory.

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