std :: vector的复制构造函数如何操作？ [英] How does std::vector's copy constructor operate?

问题描述

std :: vector< std :: string> 如何在调用以下代码时初始化其自身

How does a std::vector<std::string> initialize its self when the following code is invoked

std::vector<std::string> original;
std::vector<std::string> newVector = original;

看起来好像复制构造函数将在 std :: vector< std :: string>在 newVector = original 期间新的，但是如何引入 std :: string 覆盖 orginal ？它们是副本还是新的 std :: string 的？所以是 newVector [0] 中的内存与 original [0] 相同。

It would seem as if the copy constructor would be invoked on std::vector<std::string> new during newVector = original, but how are the std::string's brought over inside of the orginal? Are they copies or new std::string's? So is the memory in newVector[0] the same as original[0].

我问的原因是我做了以下的事情：

The reason I ask is say I do the following

#include <vector>
#include <string>
using namespace std;

vector<string> globalVector;

void Initialize() {
    globalVector.push_back("One");
    globalVector.push_back("Two");
}

void DoStuff() {
    vector<string> t = globalVector;
}

int main(void) {
    Initialize();
    DoStuff();
}

t 超出范围的 DoStuff （在非优化构建），但如果 t 只是填充指针 std :: string 在 globalVector 中，可能会调用析构函数并使用 std :: string 删除，用于使全局变量[0] 填充垃圾 std :: string '

t will fall out of scope of DoStuff (on a non optimized build), but if it t is just filled with pointers to the std::string's in globalVector, might the destructor be called and the memory used in std::string deleted, there for making globalVector[0] filled with garbage std::string's after DoStuff is called?

一个坚果壳，我基本上是问，当 std :: vector 的复制构造函数，如何复制其中的元素？

A nut shell, I am basically asking, when std::vector's copy constructor is called, how are the elements inside copied?

推荐答案

std :: vector 和大多数其他标准库容器按值存储元素。插入时或复制容器时复制元素。 std :: string 也维护自己的数据副本，就您的使用而言。

std::vector and most other standard library containers store elements by value. The elements are copied on insertion or when the container is copied. std::string also maintains its own copy of the data, as far as your usage of it is concerned.

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