move

在学习c++的线程标准库的时候同时碰到了右值引用（&&）和c++11的move构造函数， 简单的看了几篇博客，大概了解了左值、左值引用、右值、右值引用以及在左值明确放弃对其资源的所有权，通过std::move()来将其转为右值引用这五点内容： 以下链接都很简短，看两遍我相信就能有比较好的理解了： 浅析C++11右值引用和move语义 左值、左值引用、右值、右值引用 c++为什么用右值引用 一个std::move()的例程（参考： c++11 std::move() 的使用 ） #include <iostream> #include <utility> #include <vector> #include <string> int main() { std::string str = "Hello"; std::vector<std::string> v; //调用常规的拷贝构造函数，新建字符数组，拷贝数据 v.push_back(str); std::cout << "After copy, str is \"" << str << "\"\n"; //调用移动构造函数，掏空str，掏空后，最好不要使用str v.push_back(std::move(str)); std::cout << "After move, str is \"" << str << "\"\n";

报错：Call to a member function move() on a non-object 解决：加上接受参数 $file = request()->file('file'); 里边的file 必须写 文章来源: thinkphp Call to a member function move() on a non-object

To improve efficiency of std::vector<T> , it's underlying array needs to be pre-allocated and sometimes re-allocated. That, however, requires the creation and later moving of objects of type T with a copy ctor or move ctor. The problem that I am having is that T cannot be copied or moved because it contains objects that cannot be copied or moved (such as atomic and mutex ). (And, yes, I am implementing a simple thread pool.) I would like to avoid using pointers because: I do not need a level of indirection and so I do not want one. (Pointers are less efficient and increase complexity. Using

I have heard Scott Meyers say " std::move() doesn't move anything" ... but I haven't understood what it means. So to specify my question consider the following: class Box { /* things... */ }; Box box1 = some_value; Box box2 = box1; // value of box1 is copied to box2 ... ok What about: Box box3 = std::move(box1); I do understand the rules of lvalue and rvalue but what I don't understand is what is actually happening in the memory? Is it just copying the value in some different way, sharing an address or what? More specifically: what makes moving faster than copying? I just feel that

I have a directory, 'Dst Directory', which has files and folders in it and I have 'src Directory' which also has files and folders in it. What I want to do is move the contents of 'src Directory' to 'Dst Directory' and overwrite anyfiles that exist with the same name. So for example 'Src Directory\file.txt' needs to be moved to 'Dst Directory\' and overwrite the existing file.txt. The same applies for some folders, moving a folder and merging the contents with the same folder in 'dst directory' I'm currently using shutil.move to move the contents of src to dst but it won't do it if the files

I am making a game in Python and am storing dictionaries in lists as items: equipped = {} swords = { 'wooden_sword': {'name': 'Wooden Sword', 'dmg': 1} } How would I move the wooden_sword item into the equipped lists. (If i am not using correct terminology feel free to edit) You can assign the value (actually, a copy of the value) at key 'wooden_sword' in equipped dict to value from swords dict, then delete the value from swords : ... equipped['wooden_sword'] = swords['wooden_sword'].copy() del swords['wooden_sword'] print(swords) print(equipped) Output: {} {'wooden_sword': {'name': 'Wooden

i use this code this.mPhysicsWorld = new FixedStepPhysicsWorld(30, new Vector2(0, 0), false, 8, 1); this.mScene.registerUpdateHandler(this.mPhysicsWorld); final AnimatedSprite chat_sale_1 = new AnimatedSprite(2157, 638, this.mchatSaleTextureRegion); //final PhysicsHandler physicsHandler2 = new PhysicsHandler(chat_sale_1); //chat_sale_1.registerUpdateHandler(physicsHandler2); final FixtureDef chat_sale_1FixtureDef = PhysicsFactory.createFixtureDef(0, 0, 0f); mCatBody = PhysicsFactory.createBoxBody(this.mPhysicsWorld, chat_sale_1, BodyType.DynamicBody, chat_sale_1FixtureDef); //mCatBody.setColor