Why would one ever use the “in” parameter modifier in C#?

Question

So, I (think I) understand what the in parameter modifier does. But what it does appears to be quite redundant.

Usually, I\'d think tha

Answer 1

There is. When passing a struct, the in keyword allows an optimization where the compiler only needs to pass a pointer, without the risk of the method changing the content. The last is critical — it avoids a copy operation. On large structs this can make a world of difference.