[c#] C# '@' before a String

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What's the @ in front of a string for .NET?

I found this in a C# study book

DirectoryInfo dir = new DirectoryInfo(key.Key.ToString() + @":\");

The book however did not explain what the '@' symbol was for. I tried searching MSDN C# Operators but its not listed there. I can guess that it allows the developer to not have to escape a '\' or does it allow to not have any escape sequences?

What is this for and why would I use @":\" instead of ":\\"?

Thanks for the help

Edit: See the comment below for a similar question

It also means you can use reserved words as variable names

say you want a class named class, since class is a reserved word, you can instead call your class class:

IList<Student> @class = new List<Student>();

What is this for and why would I use @":\" instead of ":\"?

Because when you have a long string with many \ you don't need to escape them all and the \n, \r and \f won't work too.

As a side note, you also should keep in mind that "escaping" means "using the back-slash as an indicator for special characters". You can put an end of line in a string doing that, for instance:

String foo = "Hello\

There";

Prefixing the string with an @ indicates that it should be treated as a literal, i.e. no escaping.

For example if your string contains a path you would typically do this:

string path = "c:\\mypath\\to\\myfile.txt";

The @ allows you to do this:

string path = @"c:\mypath\to\myfile.txt";

Notice the lack of double slashes (escaping)