const_iterators 更快吗?

问题描述

我们的编码指南更喜欢 const_iterator，因为与普通的 iterator 相比，它们要快一些.当您使用 const_iterator 时，编译器似乎优化了代码.

Our coding guidelines prefer const_iterator, because they are a little faster compared to a normal iterator. It seems like the compiler optimizes the code when you use const_iterator.

这真的正确吗?如果是，那么内部究竟发生了什么使 const_iterator 更快?.

Is this really correct? If yes, what really happens internally that makes const_iterator faster?.

我写了一个小测试来检查 const_iterator 与 iterator 并发现不同的结果:

I wrote small test to check const_iterator vs iterator and found varying results:

对于迭代 10,000 个对象，const_terator 花费的时间少了几毫秒(大约 16 毫秒).但并非总是.存在两者相等的迭代.

For iterating 10,000 objects const_terator was taking a few milliseconds (around 16 ms) less. But not always. There were iterations in which both were equal.

推荐答案

如果不出意外，const_iterator 阅读 更好，因为它告诉任何阅读代码的人我"我只是在这个容器上迭代，而不是弄乱所包含的对象".

If nothing else, a const_iterator reads better, since it tells anyone reading the code "I'm just iterating over this container, not messing with the objects contained".

这是一个巨大的胜利，别介意任何性能差异.

That's a great big win, never mind any performance differences.

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