Replace (parsing "\" illegal at end of pattern)

Question

Well I have a mini program with C#, so I do this in my program

wordSearch = "T:\\"
wordReplace = "T:\\Gestion\\"
content = Regex.Replace(content, wordSearch, wordReplace);

But doesn't work. The error is:

parsing "T:\" - illegal \ at end of pattern.

Any idea ?

[Added]

Sorry! Perhaps I didn't explain well. So I try again.

I did a form taking a string for input, but if this string is "T:\", the program take "T:\". So, I save this string in variable "workShearch".

After this variable uses in:

content = Regex.Replace(content, Regex.Escape(wordSearch), Regex.Escape(wordReplace));

But this line contains an error, because wordSearch in this case is "T:\", and the program throws an exception like this:

The error in parsing "T:\" - illegal \ at end of pattern.

Thanks!

Correct me if I'm wrong, but \ is an escape sequence, that's the problem. Try this: `content = Regex.Replace(content, @wordSearch, @wordReplace);` — DatRid, Jul 09 '14 at 07:36
Yes, it's an escape sequence both in Strings and Regexes, so the correct Regex is either `"T:\\\\Gestion\\\\"` or `@"T:\Gestion\"` — Davio, Jul 09 '14 at 07:37
It's both an regex and a C# string escape character, which means it would have to be escaped twice, i.e. "T:\\\\". — Dirk, Jul 09 '14 at 07:37
The answers below are fine... but why are you using regular expressions for this? A simple string replace would suffice in this case. i.e. `content = String.Replace(wordSearch,wordReplace);` — Jcl, Jul 09 '14 at 07:38
@DatRid, Correct me if I'm wrong, but I don't think you can use the @ on variables, just on strings. The @ on variables is to distinguish them from keywords, they don't make a string variable verbatim. — Jcl, Jul 09 '14 at 07:41
@Jcl Correct me if I'm wrong, but I think you are right! My bad. — DatRid, Jul 09 '14 at 07:57
@DatRid I was really not trying to mock on the "correct me if I'm wrong" part, just didn't see you wrote the same! :-) — Jcl, Jul 09 '14 at 08:02

score 7 · Answer 1 · answered Jul 09 '14 at 07:36

7

You should escape \ in pattern. Either use "T:\\\\" or verbatim string literal ( advantage of verbatim strings is that escape sequences are not processed, which makes it easy to write):

var wordSearch = @"T:\\";
var wordReplace = @"T:\Gestion\";

content = Regex.Replace(content, wordSearch, wordReplace);

answered Jul 09 '14 at 07:36

Sergey Berezovskiy

232,247
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459

6

I think its also useful if you explain the `@` for him ;) – DatRid Jul 09 '14 at 07:37

score 2 · Answer 2 · answered Jul 09 '14 at 07:37

2

Escape your '\' again.

wordSearch = "T:\\\\"

A more elegant solution would be to use the @ modifier infront of your strings

wordSearch = @"T:\\"

answered Jul 09 '14 at 07:37

Chrisi

371
3
15

score 2 · Answer 3 · answered Jul 09 '14 at 07:38

\ is escape character, if you want to have \\, you should type \\\\ or place @ in front of your string, which will consider whole string is a plain text

wordSearch = @"T:\\"
wordReplace = @"T:\\Gestion\\"

// or 

wordSearch = "T:\\\\"
wordReplace = "T:\\\\Gestion\\\\"

Replace (parsing "\" illegal at end of pattern)

3 Answers3

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