Are value types immutable by definition?

Question

I frequently read that structs should be immutable - aren\'t they by definition?

Do you consider int to be immutable?

int i         


        

Answer 1

Objects/Structs are immutable when they are passed into a function in such a way as the data cannot be changed, and the returned struct is a new struct. The classic example is

String s = "abc";

s.toLower();

if the toLower function is written so they a new string is returned that replaces "s", it's immutable, but if the function goes letter by letter replacing the letter inside "s" and never declaring a "new String", it is mutable.