Dynamic arrays vs. std::vector

Question

I've written a small program to calculate prime numbers using the naive division algorithm. In order to improve the performance, I thought it should only check the divisibility based on previously detected primes less than equal to the number's square root. In order to do that, I need to keep track of the primes. I've implemented it using dynamic arrays. (eg Using new and delete ). Should I use std::vector instead? Which is better in terms of performance? (Maintenance is not an issue.) Any help would be appreciated. 😊

Answer 1

The ideal answer:

How should any of us know? It depends on your compiler, your OS, your architecture, your standard library implementation, the alignment of the planets...

Benchmark it. Possibly with this . (Haven't used it, but it seems simple enough to use.)

The practical answer:

Use std::vector . Every new and delete you make is a chance for a memory leak, or a double- delete , or otherwise forgetting to do something. std::vector basically does this under the hood anyway. You're more likely to get a sizeable performance boost by maxing out your optimization flags (if you're using gcc , try -Ofast and -march=native ).

Also:

Maintenance is not an issue.

Doubt it. Trust me on this one. If nothing else, at least comment your code (but that's another can of worms).

Answer 2

为了您的目的，向量可能会更好，这样您就不必担心内存管理（例如，增加数组大小并复制以前的结果），或保留太多内存来存储结果。