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

fileName = fileName.Replace(":", "-") 

However ":" is not the only illegal character for Windows. You will also have to handle:

/, \, :, *, ?, ", <, > and |

These are contained in System.IO.Path.GetInvalidFileNameChars();

Also (on Windows), "." cannot be the only character in the filename (both ".", "..", "...", and so on are invalid). Be careful when naming files with ".", for example:

echo "test" > .test.

Will generate a file named ".test"

Lastly, if you really want to do things correctly, there are some special file names you need to look out for. On Windows you can't create files named:

CON, PRN, AUX, CLOCK$, NUL
COM0, COM1, COM2, COM3, COM4, COM5, COM6, COM7, COM8, COM9
LPT0, LPT1, LPT2, LPT3, LPT4, LPT5, LPT6, LPT7, LPT8, and LPT9.