C ++转换为Objective-C

Question

I'm looking into translating some code from C++ to Objective C and I ran into an instance that contains a function with a const notation at the end. I'm quite rusty on C++ and I don't remember what this would represent (I have been googling though). I'd like to know how to force this over to Objective-C. Currently, here's what I have:

C++ code:

  float RenderingEngine1::RotationDirection() const
    {
        float delta = m_desiredAngle - m_currentAngle;
        if (delta == 0)
            return 0;

        bool counterclockwise = ((delta > 0 && delta <= 180) || (delta < -180));
        return counterclockwise ? +1 : -1;
    }

Objective-C:

-(float)getRotationDirection{
    float delta = desiredAngle - currentAngle;
    if (delta == 0) {
        return 0;
    }

    bool counterclockwise = ((delta > 0 && delta <= 180) || (delta < -180));

    float test = counterclockwise ? +1 : -1;
    NSLog(@"%f",test );
    return counterclockwise ? +1 : -1; //problem

}

Edit: found the error of my ways and it was just an addition problem somewhere else in the program ('I love the easy ones'). That being said, I do want to ensure that the const declaration will not interfere with any further issues and want to check to ensure whether or not there should be any declarations I need to make (such as singleton methods and such). Thank you guys for the answers!

Answer 1

const in c++ means that this method doesn't alter the state of the object, thus it may use just const methods, and it can't alter class variables unless they're declared mutable.

If your class is immutable, you can safely assume that every method you've declared is the equivalent of a const method.

However, since you aren't altering any ivar, you're "translating" the code properly (logically speaking), as you aren't mutating any ivar.

I don't see any particular problem with your code, there shouldn't be a syntax (neither semantic) error.

PS: That's not how you should compare floating point numbers, look here .