What is the difference between String.Empty and “” and null?

Answer 1

String.Empty because it is a static variable, rather than "" which has to create a new string, and null means that you must then set the string equal to a new instance of a string.

(thanks for the correction)

Answer 2

It is considered better practise to use string.Empty, however they are effectively equal. They are not the same as null, however.

Answer 3

Yes. And String.Empty, but please don't worry about it.

Answer 4

public sealed class String {
    //...
    public static readonly String Empty = "";
    //...
}

Use null when you want to represent that there is no value;

Use String.Empty when you want to represent that there is a value, but the value is a blank string.

Answer 5

FROM http://msdn.microsoft.com/en-us/library/system.string.empty.aspx

The value of this field is the zero-length string, "".

In application code, this field is most commonly used in assignments to initialize a string variable to an empty string. To test whether the value of a string is String..::.Empty, use the IsNullOrEmpty method.

Answer 6

They are equal . But String.Empty is constant .

"" - is way of creating String .

Answer 7

Use whichever you find most readable.

I challenge anyone to find a realistic application where there's a significant performance difference... it just won't happen. However, different people find different approaches more readable.

Personally, I'm a "" person. I find it less cluttered, and I've never encountered a problem where I actually used " " (or something similar) accidentally. (That's one of the objections frequently raised.)

If you prefer string.Empty, I'm certainly not going to claim you're "wrong". I would suggest, however, that if you're working on a team you discuss it to find out what most people think is more readable, and stick to that. Consistency is generally a good thing.

EDIT: Just to allay some fears which might be induced by the claim that "" will create a new string... it may create a new string once (possibly per AppDomain, possibly per process; I'm not sure and it really doesn't matter). It won't create a new string every time you use it. For example, consider this code:

public void Foo()
{
    string x = "";
    for (int i=0; i < 10000000; i++)
    {
        string y = "";
        // Do something here
    }
    string z = "";
}

You are guaranteed that x, y and z will refer to the same string. At most, invoking Foo will mean a single empty string is created, and only the first time you call it, and only if you haven't used an empty string literal anywhere else in the program yet. The code above is not going to create 10 million new strings.

Answer 8

The answer you are looking for is here.

http://stackoverflow.com/questions/151472/what-is-the-difference-between-string-empty-and/151481#151481

use String.Empty

Answer 9

null and empty are not equal..