In the C# language file, the only supported strings are C++ style strings.  However, C# has a string format called "Verbatim String Literals.":

    string foo = "a\\b\\c";

is equivalent to:

    string foo = @"a\b\c";

and

    string bar = "a\"b\"c";

is equivalent to:

    string bar = @"a""b""c";

Basically, any character other than a double-quote is handled as though it is part of the string.  Double-quotes are doubled-up to  encode a double-quote character.

The EBNF for string literals in C# is available here:
http://msdn.microsoft.com/en-us/library/aa691090%28v=vs.71%29.aspx