Is there a difference between x => x + 1 and x => x += 1?

Question

I'm currently learning functional programming, and I was wondering if there is a difference between these functions.

Func<int, int> incrementByOne = x => x += 1;
Func<int, int> incrementByOne2 = x => x + 1;

Answer 1

There is no difference. Because:

1. int is a value type, so passed by value (being copied), thus in x => x += 1 changing x cannot affect the source (no side effects)
2. += returns the result of addition, so the same as + does