C ++比较双打

Question

Is there any known problem using < or > with doubles?

d1 > d2

d2 > d1

I cannot find anything that would indicate that this would be a problem.

However, I assume this will be a problem due to the issues with equality and I will have to use "almost equal" logic using Epsilon:

d1 >= d2

d2 >= d1

Answer 1

> and < work exactly as expected; if the value of d1 is greater than the value of d2 , then d1 > d2 will be true (and vice versa). The problem (if there is one) is that d1 and d2 might not be exactly the values you expected.

However, replacing > with >= will change the behaviour for exactly one value of d1 (for a fixed value of d2 ).

Answer 2

The only problem is that you may get a 'false positive' where there are two variables d1 and d2 which you deem to be of equal value. In that case if you do d1 > d2 , there is a chance the expression will evaluate to true.