2个指向相同分配内存的矢量对象 [英] 2 vector objects pointing to the same allocated memory

问题描述

在C ++中，如何复制指向相同分配内存的现有向量？

In C++, how to make a copy of an existing vector pointing to the same allocated memory ?

例如：

vector<int> o1;
o1.push_back(1);

vector<int> o2;
//Make o2 share same memory as o1
o2[0]=2;

cout << o1[0]; //display 2

编辑：我不清楚目标：如果o1分配给堆并被销毁，如何创建一个对象o2，该对象将指向与o1相同的已分配内存，以使其保持在o1范围之外？

EDIT : I haven't been clear about the objective : if o1 is allocated on the heap and gets destroyed, how can I create an object o2 that would point to the same allocated memory as o1 to keep it outside of the o1 scope ?

推荐答案

有一个 boost :: shared_array 模板。

但这共享一个固定的-大小的数据数组，您不能修改大小。

This however shares a fixed-size array of data and you cannot modify the size.

如果要共享可调整大小的矢量，请使用

If you want to share a resizeable vector then use

boost :: shared_ptr<向量<整数> >

您还可以做的是将向量存储器 swap 换成另一个

What you can also do is swap the vector memory into a different vector.

{
   std::vector< int > o1; // on the stack
     // fill o1
   std::vector< int > * o2 = new std::vector< int >; // on the heap
   o2->swap( o1 );
    // save o2 somewhere or return it
} // o2 now owns the exact memory that o1 had as o1 loses scope

C ++ 11 将引入移动语义，允许您使用 std :: move 因此

C++11 will bring in "move" semantics allowing you to keep the actual memory in o1 with std::move thus

std::vector<int> && foo()
{
      std::vector<int> o1;
       // fill o1
      return std::move( o1 );
}


// from somewhere else
std::vector< int > o2( foo() );

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