Develop Reference

Regex - Extracting File Paths

I need to be able to extract the full file path out of this string (without whatever is after the file extension):
$/FilePath/FilePath/KeepsGoing/Folder/Script.sql (CS: 123456)
A simple solution such as the following could would work for this case, however it is only limited to a file extension with 3 characters:
(\$.*\..{3})
However, I find problems with this when the file contains multiple dots:
$/FilePath/FilePath/File.Setup.Task.exe.config (CS: 123456)
I need to be able to capture the full file path (from $ to the end of whatever the file extension is, which can be any number of things). I need to be able to get this no matter how many dots are in the name of the file. In some cases there are spaces in the name of the file too, so I need to be able to incorporate that.
Edit: The ending (CS....) in this case is not standard. All kinds of stuff can follow the path so I cannot predict what will come after the path, but the path will always be first. Sometimes spaces do exist in the file name.
Any suggestions?

Try this:
(\$.*\.[\w.-]+)
But! it will not properly match files with space or special chars in the file extension. If you need to match files that might have special chars in the file extension you'll need to elaborate on the input (is it quoted? is it escaped?).

Why is Path.Combine better than "\\"?

Over the years, and again recently, I have heard discussion that everyone should use Path.Combine instead of joining strings together with "\\", for example:
string myFilePath = Path.Combine("c:", "myDoc.txt");
// vs.
string myFilePath = "C:" + "\\myDoc.txt";
I'm failing to see the benefit that the former version provides over the latter and I was hoping someone could explain.

Building a path with Path.Combine is more readable and less error-prone. You don't need to think about directory separator chars(\\ or \ or / on unix, ...) or if the first part of the path does or does not end in \ and whether the second part of the path does or does not start with \.
You can concentrate on the important part, the directories and filenames. It's the same advantage that String.Format has over string concatenation.

When you don't know the first directory (e.g. it comes from user input), you may have C:\Directory or C:\Directory\ and Path.Combine will solve the trailing slash problem for you. It does have quirks with leading slashes for the next arguments though.
Second, while usually not a problem for most applications, with Path.Combine you aren't hard-coding the platform directory separator. For an application that can be deployed to other operating systems than windows this is convenient.

Other platforms can use a different Separator, for example / instead of \ so the reason for not using \\ is to be S.O. independent

In this case, it does not really matter, but why don't you just write:
string myFilePath = "C:\\myDoc.txt";
The Path.Combine() method is useful if you are working with path variables and you don't want to check for backslashes (or whatever slashing required, depending on the platform):
string myFilePath = Path.Combine(path, filename);

Passing 2 filepaths with spaces via commandline to a C# application

I am trying to pass two directory paths via the command line to a C# application. These paths will likely contain spaces, and given that C# populates args[] by splitting across spaces, this is giving me problems.
What I tried was passing the paths wrapped in quotes, like this:
myprogram.exe "C:\aa a\bbb\" "C:\ppp\ll l\"
..this, however, creates a problem because the backslash at the end of each path is being interpreted by C# as an escape character, so it is parsing the double quote as well. When I run the app with these argurments, args[] contains only one entry:
C:\aa a\bbb" C:\ppp\ll l"
The easy solution would be to only enter directory paths without the final backslash, but it is not optimal and will likely frustrate users of the program.
Is there an easy solution to this?

Did you try to pass them "twiced" ?
myprogram.exe "C:\\aa a\\bbb\\" "C:\\ppp\\ll l\\"

C# - Regex for file paths e.g. C:\test\test.exe

I am currently looking for a regex that can help validate a file path e.g.:
C:\test\test2\test.exe

I decided to post this answer which does use a regular expression.
^(?:[a-zA-Z]\:|\\\\[\w\.]+\\[\w.$]+)\\(?:[\w]+\\)*\w([\w.])+$
Works for these:
\\test\test$\TEST.xls
\\server\share\folder\myfile.txt
\\server\share\myfile.txt
\\123.123.123.123\share\folder\myfile.txt
c:\folder\myfile.txt
c:\folder\myfileWithoutExtension
Edit: Added example usage:
if (Regex.IsMatch (text, #"^(?:[a-zA-Z]\:|\\\\[\w\.]+\\[\w.$]+)\\(?:[\w]+\\)*\w([\w.])+$"))
{
// Valid
}
*Edit: * This is an approximation of the paths you could see. If possible, it is probably better to use the Path class or FileInfo class to see if a file or folder exists.

I would recommend using the Path class instead of a Regex if your goal is to work with filenames.
For example, you can call Path.GetFullPath to "verify" a path, as it will raise an ArgumentException if the path contains invalid characters, as well as other exceptiosn if the path is too long, etc. This will handle all of the rules, which will be difficult to get correct with a Regex.

This is regular expression for Windows paths:
(^([a-z]|[A-Z]):(?=\\(?![\0-\37<>:"/\\|?*])|\/(?![\0-\37<>:"/\\|?*])|$)|^\\(?=[\\\/][^\0-\37<>:"/\\|?*]+)|^(?=(\\|\/)$)|^\.(?=(\\|\/)$)|^\.\.(?=(\\|\/)$)|^(?=(\\|\/)[^\0-\37<>:"/\\|?*]+)|^\.(?=(\\|\/)[^\0-\37<>:"/\\|?*]+)|^\.\.(?=(\\|\/)[^\0-\37<>:"/\\|?*]+))((\\|\/)[^\0-\37<>:"/\\|?*]+|(\\|\/)$)*()$
And this is for UNIX/Linux paths
^\/$|(^(?=\/)|^\.|^\.\.)(\/(?=[^/\0])[^/\0]+)*\/?$
Here are my tests:
Win Regex
Unix Regex
These works with Javascript
EDIT
I've added relative paths, (../, ./, ../something)
EDIT 2
I've added paths starting with tilde for unix, (~/, ~, ~/something)

The proposed one is not really good, this one I build for XSD, it's Windows specific:
^(?:[a-zA-Z]\:(\\|\/)|file\:\/\/|\\\\|\.(\/|\\))([^\\\/\:\*\?\<\>\"\|]+(\\|\/){0,1})+$

Try this one for Windows and Linux support: ((?:[a-zA-Z]\:){0,1}(?:[\\/][\w.]+){1,})

I use this regex for capturing valid file/folder paths in windows (including UNCs and %variables%), with the exclusion of root paths like "C:\" or "\\serverName"
^(([a-zA-Z]:|\\\\\w[ \w\.]*)(\\\w[ \w\.]*|\\%[ \w\.]+%+)+|%[ \w\.]+%(\\\w[ \w\.]*|\\%[ \w\.]+%+)*)
this regex does not match leading spaces in path elements, so
"C:\program files" is matched
"C:\ pathWithLeadingSpace" is not matched
variables are allowed at any level
"%program files%" is matched
"C:\my path with inner spaces\%my var with inner spaces%" is matched

regex CmdPrompt("^([A-Z]:[^\<\>\:\"\|\?\*]+)");
Basically we look for everything that's not in the list of forbidden Windows Path Characters:
< (less than)
> (greater than)
: (colon)
" (double quote)
| (vertical bar or pipe)
? (question mark)
* (asterisk)

I know this is really old... but expanding on #agent-j's response I've added named groups, and support for period characters.
^(?<ParentPath>(?:[a-zA-Z]\:|\\\\[\w\s\.]+\\[\w\s\.$]+)\\(?:[\w\s\.]+\\)*)(?<BaseName>[\w\s\.]*?)$
I've saved this at Regexr

I found most of the answers here to be a little hit or miss.
Found a good solution here though:
https://social.msdn.microsoft.com/forums/vstudio/en-US/31d2bc84-c948-4914-8a9d-97b9e788b341/validate-a-network-folder-path
Note* - this is only for network shares - not local files
Answer:
string pattern = #"^\\{2}[\w-]+(\\{1}(([\w-][\w-\s]*[\w-]+[$$]?)|([\w-][$$]?$)))+";
string[] names = { #"\\my-network\somelocation", #"\\my-network\\somelocation",
#"\\\my-network\somelocation", #"my-network\somelocation",
#"\\my-network\\somelocation",#"\\my-network\somelocation\aa\dd",
#"\\my-network\somelocation\",#"\\my-network\\somelocation"};
foreach (string name in names)
{
if (Regex.IsMatch(name, pattern))
{
Console.WriteLine(name);
//Directory.Exists function to check if file exists
}
}

Alexander's Answer + Relative Paths
Alexander has the most correct answer thus far since it supports spaces in file names (i.e. C:\Program Files (x86)\ will match)... This aims to include relative paths as well.
For example, you can do cd / or cd \ and it does the same thing.
Further more, if you're currently in C:\some\path\to\some\place and you type either of those commands, you end up at C:\
Even more, you should consider paths, that start with '/' as a root path (to the current drive).
(?:[a-zA-Z]:(\|/)|file://|\\|.(/|\)|/)([^,\/:*\?\<>\"\|]+(\|/){0,1})
A Modified version of Alexander's answer, however, we include paths that are relative with no leading / or drive letter, as well as / with no leading drive letter (relative to the current drive as root).

Validating File Path w/Spaces in C#

I'm something of a n00b at C# and I'm having trouble finding an answer to this, so if it's already been answered somewhere feel free to laugh at me (provided you also share the solution). :)
I'm reading an XML file into a GUI form, where certain elements are paths to files that are entered into TextBox objects. I'm looping through the controls on the form, and for each file path in each TextBox (lol there's like 20 of them on this form), I want to use File.Exists() to ensure it's a valid file.
The problem with this is that the file path can potentially contain spaces, and can potentially be valid; however File.Exists() is telling me it's invalid, based entirely on the spaces. Obviously I can't hard-code them and do something like
if (File.Exists(#"c:\Path To Stuff"))
and I tried surrounding the path with ", like
if (File.Exists("\"" + contentsOfTextBox + "\""))
but that didn't make a difference. Is there some way to do this? Can I escape the spaces somehow?
Thank you for your time. :)

File.Exists works just fine with spaces. There is something else giving you a problem I'll wager.
Make sure your XML reader isn't failing to read the filename (parts of XML do not allow spaces and some readers will throw an exception if they encounter one).

#"c:\Path To Stuff"
The above could be a directory not a file!
Hence you would want to use Directory.Exists!
#"c:\Path To Stuff\file.txt"
If you did have a file on the end of the path then you would use File.Exists!

As the answer said, File.Exists works with spaces, if you are checking for existence of a Directory however, you should be using Directory.Exists

What is the exact error that you get when File.Exists says it is invalid?
I suspect that you are passing a path to a directory and not a file, which will return false. If so, to check the presence of a directory, use Directory.Exists.

To echo Ron Warholic: make sure the process has permissions over the target folder. I just ran into the same "bug" and it turned out to be a permissions issue.

Did you remember to replace \ with \\ ?

You need to use youtStringValue.Trim() to remove spaces leading/trailing, and Replace to remove spaces in the string you do not want.
Also, rather use System.IO.Path.Combine rather to combine these strings.

You can use # on string variables:
string aPath = "c:\Path To Stuff\text.txt";
File.Exists(#aPath);
That should solve any escape character problems because I don't think this really looks like the spaces being the problem.

hi this is not difficult if you can convert the name of the path to a string array then go through one by one and remove the spaces
once that is done just write() to the screen where you have the files, if it is xml then your xmlmapper will suffice
file.exists() should only be used in certain circumstances if you know that it does exist but not when there can be space chars or any other possible user input