string pool

[Guest]

Hi!

Is there a string pool in .NET like in Java? Is there any difference between
== and Equals() for string?

If I do the following:
string s1 = "hello";
string s2 = "hello";

Will s2 reference the same object as s1?

Thanks.

 

[David Browne]

Hi!

Is there a string pool in .NET like in Java? Is there any difference
between
== and Equals() for string?

If I do the following:
string s1 = "hello";
string s2 = "hello";

Will s2 reference the same object as s1?

In .NET it's called the "intern pool". All literal strings are "interned",
and you can intern an arbitrary string with String.Intern().
http://msdn.microsoft.com/library/d...ef/html/frlrfsystemstringclassinterntopic.asp

David

 

[Niki Estner]

Hi!

Is there a string pool in .NET like in Java? Is there any difference
between
== and Equals() for string?

Yes, but not every string gets pooled. See http://tinyurl.com/4vl42 for
details. The Remarks section contains a godd description.

If I do the following:
string s1 = "hello";
string s2 = "hello";

Will s2 reference the same object as s1?

Yes, because string constants are automatically interned by the compiler.
This won't neccessarily work for strings created at runtime.

Niki

 

[Richard Blewett [DevelopMentor]]

Its called string interning in .NET and yes, they will reference the same object.

Regards

Richard Blewett - DevelopMentor
http://www.dotnetconsult.co.uk/weblog
http://www.dotnetconsult.co.uk

Hi!

Is there a string pool in .NET like in Java? Is there any difference between
== and Equals() for string?

If I do the following:
string s1 = "hello";
string s2 = "hello";

Will s2 reference the same object as s1?

Thanks.

 

[Bruno Jouhier [MVP]]

As the others have said, .NET has interning too.

But there is another factor to consider re. == vs. Equals:

* In Java, == always compares the references.
* In C#, == can be overloaded and can be given "value" semantics instead of
"reference" semantics, and this is the case with System.String.

So, this gives the following results:

string s1 = "hello";
string s2 = "hello";
string s3 = "hel";
s3 += "lo";

Console.WriteLine(s1 == s2); // True
Console.WriteLine((object)s1 == (object)s2); // True (interning!)
Console.WriteLine(s1 == s3); // True (operator
overloading)
Console.WriteLine((object)s1 == (object)s3); // False (s3 not
interned)

In Java, you would get true, true, false, false instead!

Warning: operator overloading only works if the types are "string" at
compile time!

Bruno.

"Vladimir Knezevic" <[email protected]> a écrit
dans le message de (e-mail address removed)...