In C# how can I prepare a string to be valid for windows directory name

Question

I am writing a C# program which reads certain tags from files and based on tag values it creates a directory structure.

Now there could be anything in those tags,

If the tag name is not suitable for a directory name I have to prepare it to make it suitable by replacing those characters with anything suitable. So that directory creation does not fail. I was using following code but I realised this is not enough..

path = path.replace("/","-");
path = path.replace("\\","-");

please advise what's the best way to do it..

thanks,

Take a look at [Path.GetInvalidFileNameChars](http://msdn.microsoft.com/en-us/library/system.io.path.getinvalidfilenamechars.aspx) and [Path.GetInvalidPathChars](http://msdn.microsoft.com/en-us/library/system.io.path.getinvalidpathchars.aspx) — Marlon, Apr 10 '12 at 01:24
I've got a blog post covering how to write a WPF ValidationRule to validate this very thing, it's got a bunch of code you can rip from it: [*Taking data binding, validation and MVVM to the next level - part 2*](http://techfilth.blogspot.co.nz/2011/07/taking-data-binding-validation-and-mvvm.html). I mention this because there can be a bunch of edge cases when dealing with path and file names. — slugster, Apr 12 '12 at 00:25

Nikhil Agrawal · Answer 1 · 2016-04-04T08:57:47.853

Import System.IO namespace and for path use

Path.GetInvalidPathChars

and for filename use

Path.GetInvalidFileNameChars

For Eg

string filename = "salmnas dlajhdla kjha;dmas'lkasn";

foreach (char c in Path.GetInvalidFileNameChars())
    filename = filename.Replace(System.Char.ToString(c), "");

foreach (char c in Path.GetInvalidPathChars())
    filename = filename.Replace(System.Char.ToString(c), "");

Then u can use Path.Combine to add tags to create a path

string mypath = Path.Combine(@"C:\", "First_Tag", "Second_Tag"); 

//return C:\First_Tag\Second_Tag

Reed Copsey · Accepted Answer · 2012-04-10T05:07:08.240

3

You can use the full list of invalid characters here to handle the replacement as desired. These are available directly via the Path.GetInvalidFileNameChars and Path.GetInvalidPathChars methods.

edited Apr 10 '12 at 05:07

answered Apr 10 '12 at 01:21

Reed Copsey

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score 2 · Answer 3 · answered Apr 10 '12 at 01:40

The characters you must now use are: ? < > | : \ / * "

    string PathFix(string path)
    {
        List<string> _forbiddenChars = new List<string>();
        _forbiddenChars.Add("?");
        _forbiddenChars.Add("<");
        _forbiddenChars.Add(">");
        _forbiddenChars.Add(":");
        _forbiddenChars.Add("|");
        _forbiddenChars.Add("\\");
        _forbiddenChars.Add("/");
        _forbiddenChars.Add("*");
        _forbiddenChars.Add("\"");

        for (int i = 0; i < _forbiddenChars.Count; i++)
        {
            path = path.Replace(_forbiddenChars[i], "");
        }

        return path;
    }

Tip: You can't include double-quote ("), but you can include 2 quotes (''). In this case:

    string PathFix(string path)
    {
        List<string> _forbiddenChars = new List<string>();
        _forbiddenChars.Add("?");
        _forbiddenChars.Add("<");
        _forbiddenChars.Add(">");
        _forbiddenChars.Add(":");
        _forbiddenChars.Add("|");
        _forbiddenChars.Add("\\");
        _forbiddenChars.Add("/");
        _forbiddenChars.Add("*");
        //_forbiddenChars.Add("\""); Do not delete the double-quote character, so we could replace it with 2 quotes (before the return).

        for (int i = 0; i < _forbiddenChars.Count; i++)
        {
            path = path.Replace(_forbiddenChars[i], "");
        }

        path = path.Replace("\"", "''"); //Replacement here
        return path;
    }

You'll of course use only one of those (or combine them to one function with a bool parameter for replacing the quote, if needed)

score 1 · Answer 4 · edited May 23 '17 at 11:59

The correct answer of Nikhil Agrawal has some syntax errors.

Just for the reference, here is a compiling version:

public static string MakeValidFolderNameSimple(string folderName)
{
    if (string.IsNullOrEmpty(folderName)) return folderName;

    foreach (var c in System.IO.Path.GetInvalidFileNameChars())
        folderName = folderName.Replace(c.ToString(), string.Empty);

    foreach (var c in System.IO.Path.GetInvalidPathChars())
        folderName = folderName.Replace(c.ToString(), string.Empty);

    return folderName;
}

In C# how can I prepare a string to be valid for windows directory name

4 Answers4