Short-circuiting and readability

Question

In this line

if ((last_search == NULL) || (last_search != NULL && total_results != 0))

I know that C's short-circuit evaluation rules say that only if last_search is not null will it try and evaluate the right-hand side of ||, hence it's equivalent to writing

if ((last_search == NULL) || (total_results != 0))

and I was advised to use the later by someone, but still isn't the former more readable? Also won't the compiler optimize out the redundant last_search != NULL?

Answer 1

This is subjective, but no, the first variant is not more readable because there's more to read. The most readable code (and the least buggy!) is that which does not exist. Just think what would happen if you wanted to check 3 or 4 conditions at once.

And here's another counterexample: would you write code like this?

if (number < 0) {
}
else if(number >= 0) {
    // why not just "else"?
}

As for performance: the compiler would probably optimize the redundant call away, but undoing the performance degradation does not help with the readability degradation.