Double Negation in C++

Question

I just came onto a project with a pretty huge code base.

I\'m mostly dealing with C++ and a lot of the code they write uses double negation for their boolean logic.

Answer 1

As Marcin mentioned, it might well matter if operator overloading is in play. Otherwise, in C/C++ it doesn't matter except if you're doing one of the following things:

• direct comparison to true (or in C something like a TRUE macro), which is almost always a bad idea. For example:

  if (api.lookup("some-string") == true) {...}

• you simply want something converted to a strict 0/1 value. In C++ an assignment to a bool will do this implicitly (for those things that are implicitly convertible to bool). In C or if you're dealing with a non-bool variable, this is an idiom that I've seen, but I prefer the (some_variable != 0) variety myself.

I think in the context of a larger boolean expression it simply clutters things up.