Thread: What's the best way to make an expression evaluate as a double?

Originally Posted by King Mir

That's why the minimal solution is to convert the 2. Alternatively you could cast MARGIN. Anything else and the result may be different. That's why the safest approach is to cast everything, and write everything in terms of doubles. Then there is less room for error.

For example, casting WIDTH is not sufficient if MARGIN*2 will overflow an int (or whatever larger size MARGIN is).

Which has always been the prevailing argument for using consts over #defines for magic numbers.

I have seen a lot of people who prefer for magic numbers to be explicitly assigned to a constant variable. Though you could always define them with an explicit cast too. Or just cast them as you said. But assuming there is no explicit cast defined, then you won't need a cast at all since everything will be promoted to a double until the point where you assign it to a non-double valued variable.