const_iterators更快吗？ [英] Are const_iterators faster?

问题描述

我们的编码指南喜欢 const_iterator ，因为它们比正常的迭代器快一点。在使用 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.

这是真的吗？如果是的话，在内部真正发生了什么使 const_iterator 更快？

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

编辑：我写了小测试检查 const_iterator vs 迭代器并找到不同的结果：

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

10,000个对象 const_terator 花费了几毫秒（大约16毫秒）。但不总是。

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

如果没有别的，一个 const_iterator 更好，因为它告诉任何人阅读的代码我只是迭代这个容器，不搞乱对象包含。

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".

这是一个伟大的胜利，不介意任何表现差异。

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

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