C#: Good/Best implementation of Swap method

Question

I read this post about card shuffling and in many shuffling and sorting algorithms you need to swap two items in a list or array. But what does a good and effecient Swap method look like? Lets say for a T[] and for a List<T>. How would you best implement a method that swaps two items in those two?

Swap(ref cards[i], ref cards[n]);   // How is Swap implemented?

Answer 1

A good swap is one where you don't swap the contents. In C/C++ this would be akin to swapping pointers instead of swapping the contents. This style of swapping is fast and comes with some exception guarantee. Unfortunately, my C# is too rusty to allow me to put it in code. For simple data types, this style doesn't give you much. But once you are used to, and have to deal with larger (and more complicated) objects, it can save your life.

Answer 2

void swap(int &a, int &b)

    { // &a != &b
      //  a ==  b OK 
     a ^= b;
     b ^= a;
     a ^= b;
     return;
    }

edit: did not realize i was in c# section. is c++ code but should have same basic idea. Believe ^ is XOR in c# as well. looks like instead of & you may need "ref"? not sure.