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

Question

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 \

Answer 1

Cleaning a little my code and making a little refactoring... I created an extension for string type:

public static string ToValidFileName(this string s, char replaceChar = '_', char[] includeChars = null)
{
  var invalid = Path.GetInvalidFileNameChars();
  if (includeChars != null) invalid = invalid.Union(includeChars).ToArray();
  return string.Join(string.Empty, s.ToCharArray().Select(o => o.In(invalid) ? replaceChar : o));
}

Now it's easier to use with:

var name = "Any string you want using ? / \ or even +.zip";
var validFileName = name.ToValidFileName();

If you want to replace with a different char than "_" you can use:

var validFileName = name.ToValidFileName(replaceChar:'#');

And you can add chars to replace.. for example you dont want spaces or commas:

var validFileName = name.ToValidFileName(includeChars: new [] { ' ', ',' });

Hope it helps...

Cheers