How to use $ symbol in Regex.Replace method?

Question

I have a string like following:

string strAttachment = "3469$cosmeticsview@.png,3470SQL.txt";  

i want this:

cosmeticsview.png,SQL.txt

i try this:

var result = Regex.Replace(strAttachment, @"\d+@+$", "");
Response.Write(result);

but not work.

i think causes this problem is $ symbol.

Edit

I want remove digits also

Answer 1

try escaping it like \\$

it's reserved in Regex to indicate the end of a line

Also, the @+ isn't needed - that's not how regex works. To get your desired result you want:

\\d+\\$

then use a Replace for the @ :

var result = Regex.Replace(strAttachment, @"\d+$", "").Replace("@","");

Answer 2

You have two problems here - first is escaping of special regex symbols (end of line in your case). And second one is wrong pattern - your current solution tries to match @ right after digits:

   one or more @ character
       |
       | end of line
       | |
    \d+@+$
     |
one or more digit

That will be matched by hello1234@ which, of course, not your case. You want to remove either digits with dollar sign, or @ character. Here is correct pattern:

  one optional $ character
        |
        | OR
        | |
    \d+\$?|@
     |     |
     |   @ character
     |
one or more digit

Here is code:

string strAttachment = "3469$cosmeticsview@.png,3470SQL.txt";  
var result = Regex.Replace(strAttachment, @"\d+\$?|@", "");

Alternatively, if you just want to remove any digits, dollars and @ from your string:

var result = Regex.Replace(strAttachment, @"[\d\$@]+", "");

Answer 3

I think you're complicating this by trying to make a single pass. First get the part of the string you want (eg cosmeticsview@.png,3470SQL.txt ):

var match = Regex.Match(strAttachment, @"\$(.*)");
if (!match.Success) { return; }

then strip the characters you don't want. Define a list like this somewhere:

List<char> invalidChars = new List<char> { '@' };

In my example I only added the @ .

Now just remove those characters:

var val = string.Join("",
    match.Groups[1].Value
        .Where(c => !invalidChars.Contains(c))
);

Here is a Regex 101 to prove the Regex I provided.