如何从STL的const_iterator中获取数据? [英] How to get data out of the STL's const_iterator?

问题描述

我有这样的东西:

T baseline;
list<T>::const_iterator it = mylist.begin();
while (it != mylist.end()) {
    if (it == baseline) /* <----- This is what I want to make happen */
    // do stuff
}

我的问题是我不知道如何从迭代器中提取数据.我觉得这是一个愚蠢的事情，但是我不知道该怎么做.

My problem is that I have no idea how to extract the data from the iterator. I feel like this is a stupid thing to be confused about, but I have no idea how to do it.

固定了begin.end()

EDIT : Fixed begin.end()

推荐答案

迭代器具有一个看起来"像指针的接口(但它们不一定是指针，因此不要将这个隐喻带得太远).

Iterators have an interface that "looks" like a pointer (but they are not necessarily pointers, so don't take this metaphor too far).

迭代器表示对容器中单个数据的引用.您想要的是在迭代器指定的位置访问容器的内容.您可以使用*it访问位置it的内容.同样，您可以使用it->method()在位置it上的内容上调用方法(如果内容是对象).

An iterator represents a reference to a single piece of data in a container. What you want is to access the contents of the container at the position designated by the iterator. You can access the contents at position it using *it. Similarly, you can call methods on the contents at position it (if the contents are an object) using it->method().

这与您的问题并没有真正的联系，但是要提防这是一个常见的错误(即使我仍然时不时地这样做):如果位置it上的内容是指向对象的指针，以调用该对象上的方法，语法为(*it)->method()，因为存在两个间接级别.

This doesn't really relate to your question, but it is a common mistake to be on the lookout for (even I still make it from time to time): If the contents at position it are a pointer to an object, to call methods on the object, the syntax is (*it)->method(), since there are two levels of indirection.

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