C# @ symbol in variable names

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What does placing a @ in front of a C# variable name do?

Hi,

I justed picked up on Silverlight and RIA services. While creating a new domain service which supports editing, the following code was generated in the domain service class (C#):

  public void InsertClass(Class @class){
        ...
  }

What is the significance of the @ symbol in the variable name?

score 6 · Accepted Answer · answered Apr 28 '11 at 20:15

6

class is a reserved word in C# to denote a new type. You can't have a variable name that is a reserved word, so you use @ to 'escape' the symbol.

AKA:

int int = 4; // Invalid
int @int = 4; // Valid

answered Apr 28 '11 at 20:15

Tejs

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Bala R · Answer 2 · 2011-04-28T20:20:57.763

The @ is used in cases where you have to have a variable name that's also a c# reserved keyword. In most cases it can be avoided (and should be, because of the confusion it can cause). Some times it's unavoidable; for instance in asp.net MVC you have add css class to an element you have to use an anonymous class like this

new {@class = "myCssClass" }

for it to render

... class="myCssClass" ...

There's no way around it.

score 1 · Answer 3 · answered Apr 28 '11 at 20:16

1

what would happen if you tried to name a variable class, do you think? The @ prefix lets you use reserved/key words as variable names.

answered Apr 28 '11 at 20:16

Nicholas Carey

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score 1 · Answer 4 · edited May 23 '17 at 12:03

1

This was answered previously here.

The @ symbol allows you to use reserved word.

edited May 23 '17 at 12:03

Community

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answered Apr 28 '11 at 20:16

Chad

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score 1 · Answer 5 · answered Apr 28 '11 at 20:16

1

The @ sign is valid only at the beginning of a variable name and is used to allow reserved keywords to be used as variable names.

var @class = 12;  // This will compile
var cl@ss = 12; // This will NOT compile

answered Apr 28 '11 at 20:16

Kyle Trauberman

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score 1 · Answer 6 · edited Mar 27 '12 at 08:31

The @ symbol is used when you want to name variables that are also C# keywords. i.e.,

var @abstract = "1234";

would create a string called "@abstract". If you did not you would get a compile error.

Also - you can use the @ sign in front of strings:

var myStr = @"C:\MyDataFile.txt";

This way, you don't have to escape literals inside the string. Normally you would have had to use a double \ after C:

C# @ symbol in variable names

6 Answers6