C #에서 string.Empty 또는 String.Empty 또는 ""를 사용하여 문자열을 초기화해야합니까?

C #에서 string.Empty 또는 String.Empty 또는 ""를 사용하여 문자열을 초기화해야합니까?

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C #에서는 빈 문자열로 문자열 값을 초기화하고 싶습니다.

어떻게해야합니까? 올바른 방법은 무엇이며 그 이유는 무엇입니까?

string willi = string.Empty;

또는

string willi = String.Empty;

또는

string willi = "";

또는 무엇을?

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당신과 당신의 팀이 가장 읽기 쉬운 것을 사용하십시오.

다른 답변은를 사용할 때마다 새 문자열이 생성되도록 제안했습니다 "". 이것은 사실이 아닙니다. 문자열 인터 닝으로 인해 어셈블리 당 한 번 또는 AppDomain 당 한 번 (또는 전체 프로세스에 대해 한 번-확실하지 않음) 생성됩니다. 이 차이는 무시해도 될 정도 입니다. 엄청나게 무의미합니다.

그러나 더 읽기 쉬운 것은 다른 문제입니다. 주관적이며 사람마다 다를 수 있으므로 팀원 대부분이 무엇을 좋아하는지 알아 내고 일관성을 위해 모두 사용하는 것이 좋습니다. 개인적 ""으로 읽기가 더 쉽습니다.

""그리고 " "서로 쉽게 착각 할 수 있다는 주장은 나에게 잘 맞지 않는다. 당신이 비례 글꼴을 사용하는 (내가 함께 일하지 않는 한 어떤 할 개발자)는 차이를 구별하기 매우 쉽다.

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성능 및 코드 생성 관점에서 실제로 차이가 없습니다. 성능 테스트에서 그들은 한 쪽이 다른 쪽보다 더 빠르며 밀리 초 단위로 앞뒤로 이동했습니다.

비하인드 씬 코드를 살펴보면 실제로 차이가 보이지 않습니다. 유일한 차이는 IL,에 string.Empty옵 코드를 사용 ldsfld하고 ""옵 코드를 사용 ldstr,하지만 때문이다 string.Empty정적, 두 명령은 같은 일을한다. 생산 된 어셈블리를 보면 똑같습니다.

C # 코드

private void Test1()
{
    string test1 = string.Empty;    
    string test11 = test1;
}

private void Test2()
{
    string test2 = "";    
    string test22 = test2;
}

IL 코드

.method private hidebysig instance void 
          Test1() cil managed
{
  // Code size       10 (0xa)
  .maxstack  1
  .locals init ([0] string test1,
                [1] string test11)
  IL_0000:  nop
  IL_0001:  ldsfld     string [mscorlib]System.String::Empty
  IL_0006:  stloc.0
  IL_0007:  ldloc.0
  IL_0008:  stloc.1
  IL_0009:  ret
} // end of method Form1::Test1

.method private hidebysig instance void 
        Test2() cil managed
{
  // Code size       10 (0xa)
  .maxstack  1
  .locals init ([0] string test2,
                [1] string test22)
  IL_0000:  nop
  IL_0001:  ldstr      ""
  IL_0006:  stloc.0
  IL_0007:  ldloc.0
  IL_0008:  stloc.1
  IL_0009:  ret
} // end of method Form1::Test2

조립 코드

        string test1 = string.Empty;
0000003a  mov         eax,dword ptr ds:[022A102Ch] 
0000003f  mov         dword ptr [ebp-40h],eax 

        string test11 = test1;
00000042  mov         eax,dword ptr [ebp-40h] 
00000045  mov         dword ptr [ebp-44h],eax 

        string test2 = "";
0000003a  mov         eax,dword ptr ds:[022A202Ch] 
00000040  mov         dword ptr [ebp-40h],eax 

        string test22 = test2;
00000043  mov         eax,dword ptr [ebp-40h] 
00000046  mov         dword ptr [ebp-44h],eax 

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최고의 코드는 코드가 전혀 없다는 것입니다 .

코딩의 근본적인 특성은 프로그래머로서 우리의 임무는 우리가 내리는 모든 결정이 트레이드 오프라는 것을 인식하는 것입니다. […] 간결하게 시작하십시오. 테스트에서 필요에 따라 다른 차원을 늘리십시오.

Consequently, less code is better code: Prefer "" to string.Empty or String.Empty. Those two are six times longer with no added benefit — certainly no added clarity, as they express the exact same information.

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One difference is that if you use a switch-case syntax, you can't write case string.Empty: because it's not a constant. You get a Compilation error : A constant value is expected

Look at this link for more info: string-empty-versus-empty-quotes

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I'd prefer string to String. choosing string.Empty over "" is a matter of choosing one and sticking with it. Advantage of using string.Empty is it is very obvious what you mean, and you don't accidentally copy over non-printable characters like "\x003" in your "".

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I wasn't going to chime in, but I'm seeing some wrong info getting tossed out here.

I, personally, prefer string.Empty. That's a personal preference, and I bend to the will of whatever team I work with on a case-by-case basis.

As some others have mentioned, there is no difference at all between string.Empty and String.Empty.

Additionally, and this is a little known fact, using "" is perfectly acceptable. Every instance of "" will, in other environments, create an object. However, .NET interns its strings, so future instances will pull the same immutable string from the intern pool, and any performance hit will be negligible. Source: Brad Abrams.

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I personally prefer "" unless there is a good reason to something more complex.

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String.Empty and string.Empty are equivalent. String is the BCL class name; string is its C# alias (or shortcut, if you will). Same as with Int32 and int. See the docs for more examples.

As far as "" is concerned, I'm not really sure.

Personally, I always use string.Empty.

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Just about every developer out there will know what "" means. I personally encountered String.Empty the first time and had to spend some time searching google to figure out if they really are the exact same thing.

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This topic is pretty old and long, so excuse me if this behavior has been mentioned somewhere else. (And point me to the answer that covers this)

I have found a difference in the behavior of the compiler if you use string.Empty or double quotes. The difference shows itself if you don't use the string variable initialized with string.Empty or with double quotes.

In case of initialization with string.Empty then the Compiler Warning

CS0219 - The variable 'x' is assigned but its value is never used

is never emitted while in case of initialization with double quotes you get the expected message.

This behavior is explained in the Connect article at this link: https://connect.microsoft.com/VisualStudio/feedback/details/799810/c-warning-cs0219-not-reported-when-assign-non-constant-value

Basically, if I get it right, they want to allow a programmer to set a variable with the return value of a function for debugging purposes without bothering him with a warning message and thus they limited the warning only in case of costant assignments and string.Empty is not a constant but a field.

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Any of the above.

There are many, many better things to pontificate. Such as what colour bark suits a tree best, I think vague brown with tinges of dulcet moss.

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I performed this very simple test using following method in a console application:

private static void CompareStringConstants()
{
    string str1 = "";
    string str2 = string.Empty;
    string str3 = String.Empty;
    Console.WriteLine(object.ReferenceEquals(str1, str2)); //prints True
    Console.WriteLine(object.ReferenceEquals(str2, str3)); //prints True
}

This clearly suggests that all three variables namely str1, str2 and str3 though being initialized using different syntax are pointing to the exactly same string (of zero length) object in memory . I performed this test in .NET 4.5 console application. So internally they have no difference and it all boils down to convenience of which one you want to use as a programmer. This behavior of string class is known as string interning in .NET. Eric Lippert has a very nice blog here describing this concept.

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I strongly prefer String.Empty, aside from the other reasons to ensure you know what it is and that you have not accidentally removed the contents, but primarily for internationalization. If I see a string in quotes then I always have to wonder whether that is new code and it should be put into a string table. So every time code gets changed/reviewed you need to look for "something in quotes" and yes you can filter out the empty strings but I tell people it is good practice to never put strings in quotes unless you know it won't get localized.

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string is synonym for System.String type, They are identical.

Values are also identical: string.Empty == String.Empty == ""

I would not use character constant "" in code, rather string.Empty or String.Empty - easier to see what programmer meant.

Between string and String I like lower case string more just because I used to work with Delphi for lot of years and Delphi style is lowercase string.

So, if I was your boss, you would be writing string.Empty

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No one mentioned that in VisualStudio String is color coded differently then string. Which is important for readability. Also, lower case is usually used for vars and type, not a big deal but String.Empty is a constant and not a var or type.

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I doesn't make a difference. The last one is the quickest to type though :)

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It doesn't matter - they are exactly the same thing. However, the main thing is that you must be consistent

p.s. I struggle with this sort of "whats the right thing" all the time.

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It is totally a code-style preference, do to how .NET handles strings. However, here are my opinions :)

I always use the BCL Type names when accessing static methods, properties and fields: String.Empty or Int32.TryParse(...) or Double.Epsilon

I always use the C# keywords when declaring new instances: int i = 0; or string foo = "bar";

I rarely use undeclared string literals as I like to be able to scan the code to combine them into reusable named constants. The compiler replaces constants with the literals anyway so this is more of a way to avoid magic strings/numbers and to give a little more meaning to them with a name. Plus changing the values is easier.

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I would favor string.Empty over String.Empty because you can use it without needing to include a using System; in your file.

As for the picking "" over string.Empty, it is personal preference and should be decided by your team.

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I use the third, but of the other two the first seems less odd. string is an alias for String, but seeing them across an assignment feels off.

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Either of the first two would be acceptable to me. I would avoid the last one because it is relatively easy to introduce a bug by putting a space between the quotes. This particular bug would be difficult to find by observation. Assuming no typos, all are semantically equivalent.

[EDIT]

Also, you might want to always use either string or String for consistency, but that's just me.

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I have personally witnessed "" resulting in (minor) problems twice. Once was due to a mistake of a junior developer new to team-based programming, and the other was a simple typo, but the fact is using string.Empty would have avoided both issues.

Yes, this is very much a judgement call, but when a language gives you multiple ways to do things, I tend to lean toward the one that has the most compiler oversight and strongest compile-time enforcement. That is not "". It's all about expressing specific intent.

If you type string.EMpty or Strng.Empty, the compiler lets you know you did it wrong. Immediately. It simply will not compile. As a developer you are citing specific intent that the compiler (or another developer) cannot in any way misinterpret, and when you do it wrong, you can't create a bug.

If you type " " when you mean "" or vice-versa, the compiler happily does what you told it to do. Another developer may or may not be able to glean your specific intent. Bug created.

Long before string.Empty was a thing I've used a standard library that defined the EMPTY_STRING constant. We still use that constant in case statements where string.Empty is not allowed.

Whenever possible, put the compiler to work for you, and eliminate the possibility of human error, no matter how small. IMO, this trumps "readability" as others have cited.

Specificity and compile time enforcement. It's what's for dinner.

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The compiler should make them all the same in the long run. Pick a standard so that your code will be easy to read, and stick with it.

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I was just looking at some code and this question popped into my mind which I had read some time before. This is certainly a question of readability.

Consider the following C# code...

(customer == null) ? "" : customer.Name

vs

(customer == null) ? string.empty : customer.Name

I personally find the latter less ambiguous and easier to read.

As pointed out by others the actual differences are negligible.

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I use "" because it will be colored distinctively yellow in my code... for some reason String.Empty is all white in my Visual Studio Code theme. And I believe that matters to me the most.

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I think the second is "proper," but to be honest I don't think it will matter. The compiler should be smart enough to compile any of those to the exact same bytecode. I use "" myself.

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While difference is very, VERY little, the difference still exist.

1) "" creates object while String.Empty does not. But this object will be created once and will be referenced from the string pool later if you have another "" in the code.

2) String and string are the same, but I would recommend to use String.Empty (as well as String.Format, String.Copy etc.) since dot notation indicates class, not operator, and having class starting with capital letter conforms to C# coding standards.

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On http://blogs.msdn.com/b/brada/archive/2003/04/22/49997.aspx :

As David implies, there difference between String.Empty and "" are pretty small, but there is a difference. "" actually creates an object, it will likely be pulled out of the string intern pool, but still... while String.Empty creates no object... so if you are really looking for ultimately in memory efficiency, I suggest String.Empty. However, you should keep in mind the difference is so trival you will like never see it in your code...
As for System.String.Empty or string.Empty or String.Empty... my care level is low ;-)

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The empty string is like empty set just a name that everybody uses to call "". Also in formal languages strings created from an alphabet that have zero length are called the empty string. Both set and string have a special symbol for it. Empty string: ε and empty set: ∅. If you want to talk about this zero length string you will call it the empty string so everybody knows exactly what you are referring to. Now in case you name it the empty string why not use string.Empty in code, its shows the intention is explicit. Downside is that it’s not a constant and therefore not available everywhere, like in attributes. (It's not a constant for some technical reasons, see the reference source.)

참고URL : https://stackoverflow.com/questions/263191/in-c-should-i-use-string-empty-or-string-empty-or-to-intitialize-a-string