In C++, is empty() faster than comparing the size with zero?

Re:In C++, is empty() faster than comparing the size with zero? by account42 on Friday October 29, 2021 @07:59AM (#29037456)

> It's an ABI break to add small-size optimizations to std::vector at this point so unfortunately while there's not really anything in the API requirements that would prevent it, compatibility concerns pose a formidable barrier

It's also a tradeoff as you would either need additional branching on access (this is what most std::string implementations do) and/or bloat the size of all vector objects, even those that will never fit into the static size.

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Re:In C++, is empty() faster than comparing the size with zero? by kllrnohj on Saturday October 30, 2021 @02:58PM (#29051375)

It's a tradeoff the user can make, not something the STL needs to generically know like std::string does. If you look at inlined_vector (or similar implementations), the static size is specified in a type parameter, not something automatic. So just have it be 0 if you want it to behave like std::vector does currently. As such, no downsides to adding this to the type other than the ABI breakage. Default the size to 0 and you preserve API compatibility, even.

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