检查迭代器是否有效 [英] Checking if an iterator is valid

问题描述

有任何方法来检查一个迭代器（无论是从向量，列表，deque ...）是（仍然）dereferencable，即没有被无效？

Is there any way to check if an iterator (whether it is from a vector, a list, a deque...) is (still) dereferencable, i.e. has not been invalidated?

我一直使用尝试 - catch

I have been using try-catch, but is there a more direct way to do this?

示例：（不起作用）

list<int> l;
for (i = 1; i<10; i++) {
    l.push_back(i * 10);
}

itd = l.begin();
itd++;
if (something) {
    l.erase(itd);
}

/* now, in other place.. check if itd points to somewhere meaningful */
if (itd != l.end())
{
    //  blablabla
}

推荐答案

我假设你的意思是是一个迭代器有效，它没有因为容器的更改而失效（例如，向/从向量插入/删除）。在这种情况下，不能，你不能确定一个迭代器是否（安全地）可解除。

I assume you mean "is an iterator valid," that it hasn't been invalidated due to changes to the container (e.g., inserting/erasing to/from a vector). In that case, no, you cannot determine if an iterator is (safely) dereferencable.

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