使用std :: list作为循环列表是否安全？ [英] Is it safe to use std::list as a circular list?

问题描述

所以递增或递减end（）迭代器是在标准中定义的吗？在linux上，begin（）实现为end（）++。

So incrementing or decrementing the end() iterator is defined in the standard? On linux, the begin() is implemented as end()++.

#include <list>
#include <iostream>

int main()
{
  std::list<int> numbers;
  for (int i = 0; i < 10; i++)
    numbers.push_back(i);

  auto it = numbers.begin();
  int count = 3;
  while (count)
  {
    std::cout << *it++;
    if (it == numbers.end())
    {
      ++it; // is this ok ???
      --count;
      std::cout << '\n';
    }
  }
}

所以输出总是一样的在每个平台上？

So the output always the same on every platform?

输出：

0123456789
0123456789
0123456789

推荐答案

增加从中返回的迭代器任何标准C ++库容器的 end（）都会导致未定义的行为。由于 std :: list< T> 的大多数实现所共有的实现细节，它可能会增加 list.end（）但不保证确实如此。

Incrementing the iterator returned from end() of any of the standard C++ library containers results in undefined behavior. Due to an implementation detail common to most implementations of std::list<T> it may work to increment list.end() but there is no guarantee that it does.

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