CODEWITHSUNDEEP
c#stringsyntaxcoding-styleprefix
Nathan Campos
Nathan Campos

Reputation: 29497

When Is it Better To Use @ Before a String?

In code that declares or uses a string, I usually see the developers declare it like this:

string randomString = @"C:\Random\RandomFolder\ThisFile.xml";

Instead of:

string randomString = "C:\\Random\\RandomFolder\\ThisFile.xml";

That's the only thing that I see which is better to use the @ prefix, since you don't need to do \\, but is there any other use for it when it's better than just without it?

Upvotes: 5

Views: 1417

Answers (5)

somesh
somesh

Reputation: 3578

"" and @"" are both string literals, first is regular literal but the latter is a verbatim string literal '@' prefix before any string in C# .NET (Regular string literal and Verbatim string literal in C#.NET)

Upvotes: 0

Xion
Xion

Reputation: 22770

It is especially useful for regular expressions that involve matching a backslash character explicitly. Since this is a special character in both C# strings syntax and regex syntax, it requires "double escaping". Example:

string regex = "\\\\.*\\.jpg"

Same expression using the @-notation would be more tidy:

string regex = @"\\.*\.jpg"

Upvotes: 1

Cody Gray
Cody Gray

Reputation: 244732

The @ sign indicates to the compiler that the string is a verbatim string literal, and thus does not require you to escape any of the characters. Not just the backslash, of course. No escape sequences of any kind are processed by the compiler.

Whether it's "better" or not is an extremely difficult question to answer. This is a purely stylistic choice. Some might argue that the string contents are more readable when you use a string literal, rather than having to escape all of the characters. Others might prefer consistency, where all strings that contain characters that would ordinarily require escaping would have to be escaped. This makes it easier to notice errors in code at a glance. (For what it's worth, I fall into the latter camp. All my paths have \\.)

That being said, it's extremely convenient for regular expressions, for which you'd otherwise be escaping all over the place. And since they don't look much like regular strings, there's minimal risk of confusion.

Upvotes: 9

BrunoLM
BrunoLM

Reputation: 100331

Makes Regex simpler

@"^(([\w-]+\.)+[\w-]+|([a-zA-Z]{1}|[\w-]{2,}))((([0-1]?[0-9]{1,2}|25[0-5]|2[0-4][0-9])\.([0-1]?[0-9]{1,2}|25[0-5]|2[0-4][0-9])\.([0-1]?[0-9]{1,2}|25[0-5]|2[0-4][0-9])\.([0-1]?[0-9]{1,2}|25[0-5]|2[0-4][0-9])){1}|([a-zA-Z]+[\w-]+\.)+[a-zA-Z]{2,4})$";

Multiple lines string

string s = @"testing
some

string with multiple
lines";

Upvotes: 1

Matti Virkkunen
Matti Virkkunen

Reputation: 65126

Windows path names aren't the only things with a lot of backslashes. For instance, @-strings are very useful for regular expressions because they avoid having to double-escape everything.

They can also span multiple lines, so if you ever end up having to have multi-line strings in your code, they make it a bit more convenient.

Upvotes: 5

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