Comparison operators on booleans trick

Question

In C++, the logical operators &&, ||, ! are there, which corresponds to conjunction , disjunction , negation , respectively.

But I noticed the comparison operators ==, !=, <, >, <=, >= can be used for booleans as well! Given that P and Q are booleans:

P == Q is bicontitional ,

P != Q is exclusive disjunction ,

P < Q is converse nonimplication ,

P > Q is nonimplication ,

P <= Q is implication ,

And P >= Q is converse implication .

My questions are:

1. Will the program perform better by this trick?

2. Is there any example code using this trick (in any language)?

Answer 1

Will the performance increase by this trick?

On any processor where it would have any benefit, when P and Q are simple variables, this would be simple enough that you should expect compilers to make use of it already without requiring any source code rewriting.

But keep in mind that P < Q in general has a distinct disadvantage over !P && Q: it requires evaluation of Q, when the result is already known if P evaluates to true. The same applies to all the other relational operators.

Is there any example code using this trick (in any language)?

Not as a trick, but because it arguably leads to code that's easier to understand (not any specific language):

if ((a == null) != (b == null))
  throw "a and b must either both be null, or both be non-null";

It could be written with ^. Which is easier to read is a matter of opinion.