Using the literal '@' with a string variable

I'm not sure if I understand. In your example: if helper.getFilePath() returns "c:\somepath\file.txt", there will be no problem, since the @ is only needed if you are explicitely specifying a string with "".

When Functions talk to each other, you will always get the literal path. If the XML contains c:\somepath\file.txt and your function returns c:\somepath\file.txt, then string filePath will also contain c:\somepath\file.txt as a valid path.

The @"" just makes it easier to write string literals.

string (C# Reference, MSDN)

Verbatim string literals start with @ and are also enclosed in double quotation marks. For example:

@"good morning" // a string literal

The advantage of verbatim strings is that escape sequences are not processed, which makes it easy to write, for example, a fully qualified file name:

@"c:\Docs\Source\a.txt" // rather than "c:\\Docs\\Source\\a.txt"

One place where I've used it is in a regex pattern:

string pattern = @"\b[DdFf][0-9]+\b";

If you have a string in a variable, you do not need to make a "literal" out of it, since if it is well formed, it already has the correct contents.

In C# the @ symbol combined with doubles quotes allows you to write escaped strings. E.g.

print(@"c:\mydir\dont\have\to\escape\backslashes\etc");

If you dont use it then you need to use the escape character in your strings.

http://msdn.microsoft.com/en-us/library/aa691090(VS.71).aspx

You dont need to specify it anywhere else in code. In fact doing so should cause a compiler error.

You've got it backwards. The @-operator is for turning literals into strings, while keeping all funky characters. Your path is already a string - you don't need to do anything at all to it. Just lose the @.

string filePath = helper.getFilePath();

The string returned from your helper class is not a literal string so you don't need to use the '@' character to remove the behaviour of the backslashes.