why use string constructor with char array for constants?

Question

I found this piece of code and I'd like to understand why the developer used the string constructor with a char array instead of just a literal constant string:

static string atomLang = new String("lang".ToCharArray());

Maybe he was trying to make the code more interesting :)). I am sorry about that, but I couldn't resist saying the joke. — Stelian Matei
– Stelian Matei, Commented Jun 23, 2012 at 18:08
It's probably because, if you want to initialize it with a string, you can just put static string atomLang = "lang". If you already have a string, why use new? — benjer3
– benjer3, Commented Jun 23, 2012 at 18:12

Douglas · Accepted Answer · 2012-06-23 18:29:01Z

5

The only reason I can think of is to avoid getting a reference to the interned instance of the string.

string str1 = "lang";
string str2 = "lang";
string str3 = new String("lang".ToCharArray());

Console.WriteLine(object.ReferenceEquals(str1, str2));   // Output: true
Console.WriteLine(object.ReferenceEquals(str1, str3));   // Output: false

Not that this will have any practical effects on your code (other than marginal performance differences).

edited Jun 23, 2012 at 18:29

answered Jun 23, 2012 at 18:12

Douglas

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4 Comments

Konrad Rudolph Over a year ago

It should be made clear that this will have a negative effect on performance, if any.

Douglas Over a year ago

@KonradRudolph: Yes, definitely. Although I suspect there might be rare cases where it might have a positive effect, due to avoiding contention on the same string when shared among multiple cores.

usr Over a year ago

@Douglas, the same string accesses by multiple cores results in shared cache lines which is not harmful. CPUs can share read-only cache lines.

Douglas Over a year ago

@usr: Yes, the sources I read indicated that memory contention would only occur for writes. Thanks for confirming!

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