extract fileName using Regex - regex

Question

If I want to match only fileName, i.e,
in C://Directory/FileName.cs, somehow ignore everything before FileName.cs using Regex.
How can I do it?
I need this for a Compiled UI I am working on ... can't use programming language as it only accepts Regex.
Any ideas?

Answer 1

Something like this might work:
[^/]*$
It matches all characters to the end of the line that are not "/"..
If you want to match paths that use the "\" path separator you would change the regex to:
[^\]*$
But do make sure to escape the "\" character if your programming language or environment requires it. For instance you might have to write something like this:
[^\\]*$
EDIT
I removed the leading "/" and trailing "/" as they may be confusing since they are not really part of the regEx but they are very common of representing a regular expression.
And of course, depending on the features that the regEx engine supports you may be able to use look-ahead/look-behind and capturing to craft a better regEx.

Answer 2

What language are you using? Why are you not using the standard path mechanisms of that language?
How about http://msdn.microsoft.com/en-us/library/system.io.path.aspx ?

Answer 3

Based on your comment of needing to exclude paths that do not match 'abc', try this:
^.+/(?:(?!abc)[^/])+$
Completely split out in regex comment mode, that is:
(?x) # flag to enable comments
^ # start of line
.+ # match any character (except newline)
# greedily one or more times
/ # a literal slash character
(?: # begin non-capturing group
(?! # begin negative lookahead
# (contents must not appear after the current position)
abc # literal text abc
) # end negative lookahead
[^/] # any character that is not a slash
) # end non-capturing group
+ # repeat the above nc group one or more times
# (essentially, we keep looking for non-backspaces that are not 'abc')
$ # end of line

Answer 4

The regex expression that did it for me was
[^\/]*$

Answer 5

I'm way late to the party and I'm also ignoring the requirement of regex because, as J-16 SDiZ pointed out, sometimes there is a better solution. Even though the question is 4 years old, people looking for a simple solution deserve choices.
Try using the following:
public string ConvertFileName(string filename)
{
string[] temparray = filename.Split('\\');
filename = temparray[temparray.Length - 1];
return filename;
}
This method splits the string on the "\" character, stores the resulting strings in an array and returns the last element of the array (the filename).
Though the OP seems to be writing for UNIX, it doesn't take much to figure out how to tailor it to your particular need.

Answer 6

Seeing as filename can be interpreted as the basename by some. Then, this example can extract the filename/basename for any files that may not have an extension for some reason. It can also get the last directory in the same fashion.
You can see how it works and test it here.
https://regexr.com/4ht5v
The regexp is:
.+?\\(?=\w+)|\.\w+$|\\$
Before:
C:\Directory\BaseFileName.ext
C:\Directory\BaseFileName
C:\This is a Directory\Last Directory With trailing backslash\
C:\This is a Directory\Last Directory Without trailing backslash
After:
BaseFileName
BaseFileName
Last Directory With trailing backslash
Last Directory Without trailing backslash
For the sake of completion, this is how it would work with JavaScript should anyone require it.
// Example of getting a BaseFileName from a path
var path = "C:\\Directory\\FileName.cs";
var result = path.replace(/.+?\\(?=\w+)|\.\w+$|\\$/gm,"");
console.log(result);

Answer 7

Try this (working with / and \):
[^\/|\\]*$

Answer 8

I would use: ./(.$)
The parenthesis mark a group wich is the file name.
The regular expression you use may vary dependig on the regex syntax(PCRE, POSIX)
I sugest you use a regex tool, there are several for windows and linux:
Windows - http://sourceforge.net/projects/regexcreator/
Windows - http://weitz.de/regex-coach/
Linux - kodos
Hope it helps

Answer 9

just a variation on miky's that works for both filesystem path characters:
[^\\/]*\s

Answer 10

Suppose the file name has special characters, specially when supporting MAC where special characters are allowing in filenames, server side Path.GetFileName(fileName) fails and throws error because of illegal characters in path. The following code using regex come for the rescue.
The following regex take care of 2 things
In IE, when file is uploaded, the file path contains folders aswell (i.e. c:\samplefolder\subfolder\sample.xls). Expression below will replace all folders with empty string and retain the file name
When used in Mac, filename is the only thing supplied as its safari browser and allows special chars in file name.
var regExpDir = #"(^[\w]:\\)([\w].+\w\\)";
var fileName = Regex.Replace(fileName, regExpDir, string.Empty);

Answer 11

I did this without RegEx in Powershell:
Put the link in a variable
$Link = "http://some.url/some/path/file.name"
Split the link on the "/" character
$split = $Link.Split("/")
Count the splits
$SplitCount = $Split.Count
Target the filename
$Split[$SplitCount -1]
Full code :
$Link = "http://some.url/some/path/file.name"
$Split = $Link.Split("/")
$SplitCount = $Split.Count
$Split[$SplitCount -1]

Answer 12

A rather elegant solution with lookahead and lookbehind wasn't mentioned:
(?<=.+)(?=.cs)