std::deque：如何获得指向指定索引处的元素的迭代器？

发布于 2024-08-27 22:51:47 字数 440 浏览 5 评论 0原文

我有一个 std::deque，我想在指定的索引处插入一个元素（我知道 std::list 会更好）。 deque::insert() 函数采用迭代器来指定要插入的位置。给定一个索引，如何获得指向该位置的迭代器，以便我可以将该迭代器传递给 insert() ？

例如：

void insertThing ( deque<Thing> & things, Thing thing, size_t index )
{
   deque<Thing>::iterator it = /* what do I do here? */
   things.insert ( it, thing );
}

我确信这是一个非常基本的问题，对此我表示歉意。我已经很久没有使用STL了，而且我在std::deque的成员列表中没有看到任何明显能满足我要求的东西。谢谢。

原文

I have a std::deque, and I want to insert an element at a specified index (I'm aware that std::list would be better at this). The deque::insert() function takes an iterator to specify the location to insert. Given an index, how can I get an iterator pointing to that location, so that I can pass that iterator to insert()?

For example:

void insertThing ( deque<Thing> & things, Thing thing, size_t index )
{
   deque<Thing>::iterator it = /* what do I do here? */
   things.insert ( it, thing );
}

I'm sure this is a very basic question, and I apologize for it. It's been a long time since I've used the STL, and I don't see anything in std::deque's member list that obviously does what I want. Thanks.

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甜妞爱困 2024-09-03 22:51:47

void insertThing ( deque<Thing> & things, Thing thing, size_t index )
{
   deque<Thing>::iterator it = things.begin() + index;
   things.insert ( it, thing );
}

void insertThing ( deque<Thing> & things, Thing thing, size_t index )
{
   deque<Thing>::iterator it = things.begin() + index;
   things.insert ( it, thing );
}

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慕烟庭风 2024-09-03 22:51:47

双端队列支持随机访问，所以你应该可以说

things.insert( my_deque.begin() + index, thing);

A deque supports random access, so you should be able to say

things.insert( my_deque.begin() + index, thing);

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半窗疏影 2024-09-03 22:51:47

我喜欢代码中没有警告的干净解决方案，因此 std::deque::iterator operator+ 为有符号整数代码重载，例如：

void insertThing ( deque<Thing> & things, Thing thing, size_t index )
{
   deque<Thing>::iterator it = things.begin() + index; // warning here
   things.insert ( it, thing );
}

引入警告。
所以我更喜欢更好的解决方案：

void insertThing ( deque<Thing> & things, Thing thing, size_t index )
{
   auto it = things.begin();
   std::advance(it, index);     // clean code (warnings from system headers skipped)
   things.insert ( it, thing );
}

I like clean soulution without warnings in code, so as std::deque::iterator operator+ overloaded for signed integer code like:

void insertThing ( deque<Thing> & things, Thing thing, size_t index )
{
   deque<Thing>::iterator it = things.begin() + index; // warning here
   things.insert ( it, thing );
}

Introduce warning.
So better solution I like more:

void insertThing ( deque<Thing> & things, Thing thing, size_t index )
{
   auto it = things.begin();
   std::advance(it, index);     // clean code (warnings from system headers skipped)
   things.insert ( it, thing );
}

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