Tiny Tricky Code

1. Swapping

The following piece of code is what I discovered by a glance to what my deskmate was reading:
It is about swapping and I think it can be applied to all kinds of data swapping if there is no high-level requirements involved. Until then, I was convinced that a temporary variable is inevitable in even the swapping of the simplest type. Although ccomplishing it without a temporary variable is probably the only merit of this code, it is very clever and inspiring.

The conventional way of swapping two entities:

1. void swap(in out T a, in out T b)
2. {
3.     T t = b;
4.     b = a;
5.     a = t;
6. }

The improved method:

1. void swap(in out T a, in out T b)  // T supports ^ operation in the bitwise sense    
2. {
3.     a ^= b;
   
4.     b ^= a;
   
5.     a ^= b;
   
6. }

Yes, it's that simple and easy to remember, just three XORs, despite its obscurity.