Using RegEx to replace invalid characters

Question

I have a directory with lots of folders, sub-folder and all with files in them. The idea of my project is to recurse through the entire directory, gather up all the names of the files and replace invalid characters (invalid for a SharePoint migration).

However, I'm completely unfamiliar with Regular Expressions. The characters i need to get rid in filenames are: ~, #, %, &, *, { } , \, /, :, <>, ?, -, | and "" I want to replace these characters with a blank space. I was hoping to use a string.replace() method to look through all these file names and do the replacement.

So far, the only code I've gotten to is the recursion. I was thinking of the recursion scanning the drive, fetching the names of these files and putting them in a List<string>.

Can anybody help me with how to find/replace invalid chars with RegEx with those specific characters?

Why do you want to use RegEx when string.Replace would do an adequate job? — Oded
– Oded, Commented Jun 9, 2010 at 19:46
There are some more rules for invalid folders, eg. a period at the end. See Information about the characters that you cannot use in site names, folder names, and file names in SharePoint — sschoof
– sschoof, Commented Oct 13, 2016 at 9:18

Vivin Paliath · Accepted Answer · 2010-06-09 20:08:38Z

56

string pattern = "[\\~#%&*{}/:<>?|\"-]";
string replacement = " ";

Regex regEx = new Regex(pattern);
string sanitized = Regex.Replace(regEx.Replace(input, replacement), @"\s+", " ");

This will replace runs of whitespace with a single space as well.

edited Jun 9, 2010 at 20:08

answered Jun 9, 2010 at 19:52

Vivin Paliath

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7 Comments

Tim Pietzcker Over a year ago

string pattern = "[\\~#%&*{}/:<>?|"-]"; is better - less unnecessary escaping.

Vivin Paliath Over a year ago

@Tim thanks! I will edit my solution. Most of my regex experience is in Perl where I use regex literals. So I'm not entirely sure what needs to be escaped and what doesn't in C# or Java. It's mostly trial-and-error.

Tim Pietzcker Over a year ago

I just noticed that yeahumok wanted to replace the invalid characters with a space, not the empty string. I have removed the + from my version again, expecting that he wants one space for each invalid character, even if there are several in a row.

yeahumok Over a year ago

is there a way to get rid of extra spaces? for example: Deal A & B.txt becomes Deal A B.txt (3 spaces in b/w letters) Is there any way to trim off that extra space so it looks like: Deal A B.txt (1 space b/w letters) ?

dajo Over a year ago

string pattern = @"[\\~#%&*{}/:<>?|""-]"; works better, since it also removes backslashes. The current code string pattern = "[\\~#%&*{}/:<>?|\"-]"; is a regex pattern that starts with an escaped tilde - not an escaped backslash.

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Michel de Ruiter · Accepted Answer · 2015-05-01 10:20:16Z

12

is there a way to get rid of extra spaces?

Try something like this:

string pattern = " *[\\~#%&*{}/:<>?|\"-]+ *";
string replacement = " ";

Regex regEx = new Regex(pattern);
string sanitized = regEx.Replace(input, replacement);

Consider learning a bit about regular expressions yourself, as it's also very useful in developing (e.g. search/replace in Visual Studio).

edited May 1, 2015 at 10:20

answered Jun 9, 2010 at 20:16

Michel de Ruiter

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1 Comment

yeahumok Over a year ago

also, is there any way to remove any extraneous '.' (periods) in a filename? for example: 0.0.0.1.doc How would i handle this w/o it wiping out the .doc?

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