Question

How much space does string.Empty take in CLR?
I’m guessing it’s just one byte for the NULL character.

Answer 1

No, the string is a complete object, with an object header (containing a type reference, sync block etc), length, and whatever characters are required… which will be a single null character (two bytes) and appropriate padding to round up to 4 or 8 bytes overall.

Note that although strings in .NET have a length field, they’re still null-terminated for the sake of interop. The null character is not included in the length.

Of course, string.Empty will only refer to a single object no matter how many times you use it… but the reference will be 4 or 8 bytes, so if you have:

string a = string.Empty;
string b = string.Empty;
string c = string.Empty;

that will be three references (12 or 24 bytes) all referring to the same object (which is probably around 20 or 24 bytes in size).