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The art of <=>

Here we explore:

• how <=> are == differing.
• when to use or not to use the compiler default implementations.

Prerequisites

• Being able to overload an operator, especially == and <=>.

Instructions

0. Compile and run the program. We are not fully happy with the default implementation of <=> for our Complex class, which considers 1|2 as smaller than 1.5|1.5.
1. Modify it so that the ordering is based on the norm of the complexes.
2. Because you do not use any more the default implementation of <=> you had to provide also an implementation for ==. What happens if you deduce it from <=> (using (((*this)<=>other)==0)) ?
3. Try to restore the default implementation for == only.