Question

我有以下一批代码：

std::vector<std::unique_ptr<AVLTree_GeeksforGeeks>> AVLArray(100000);

/* Let's add some objects in the vector */
AVLTree_GeeksforGeeks *avl = new AVLTree_GeeksforGeeks();
avl->Insert[2]; avl->Insert[5]; AVL->Insert[0];
unique_ptr<AVLTree_GeeksforGeeks> unique_p(avl);
AVLArray[0] = move(unique_p);
/* we do this for a number of other trees, let's say another 9...
...
...
Now the vector has objects up until AVLTree[9] */

/* Let's try iterating through its valid, filled positions */
for(auto i : AVLTree )
{
   cout << "Hey there!\n";    //This loop should print 10 "Hey there"s.
}

Ruh roh。最后一部分，for（）循环中的编译错误。

\DataStructures2013_2014\main.cpp||In function 'int main()':|
\DataStructures2013_2014\main.cpp|158|error: use of deleted function 'std::unique_ptr<_Tp, _Dp>::unique_ptr(const std::unique_ptr<_Tp, _Dp>&) [with _Tp = AVLTree_GeeksforGeeks; _Dp = std::default_delete<AVLTree_GeeksforGeeks>; std::unique_ptr<_Tp, _Dp> = std::unique_ptr<AVLTree_GeeksforGeeks>]'|
e:\codeblocks\mingw\bin\..\lib\gcc\mingw32\4.7.1\include\c++\bits\unique_ptr.h|256|error: declared here|
||=== Build finished: 2 errors, 0 warnings (0 minutes, 0 seconds) ===|

关于我做错的任何想法？

Answer 1

循环

for (auto i: AVLTree) { ... }

尝试在AVLTree.begin()和AVLTree.end()中复制范围的每个元素。当然，std::unique_ptr<T>无法复制：每个指针只有一个std::unique_ptr<T>。它不会真正复制任何东西，而是窃取它。那会很糟糕。

您想要使用引用：

for (auto& i: AVLTree) { ... }

......或者，如果你不修改它们

for (auto const& i: AVLTree) { ... }

迭代向量<unique_ptr <mytype>＆gt;使用C ++ 11 for（）循环</unique_ptr <mytype>

1 个答案: