Question

Does .net sting class support cache/pool mechansism to reduce allocation overhead?

Answer 1

String literals are interned, if that’s what you’re talking about:

string x = "hello";
string y = "hel" + "lo";
string z = "h" + "ello";

bool a = object.ReferenceEquals(x, y);
bool b = object.ReferenceEquals(y, z);

Both a and b are guaranteed to be true.

You can call string.Intern yourself, too.

However as far as normal strings go (for example, the string object returned by string.Format), the answer would be no, they’re not cached by default. But you could either create your own cache or intern them if you absolutely must. As many strings are short-lived, I suspect that in most cases it’s not worth caching.