new-operator

问题 What happens, in the following code, if construction / destruction of some array element throws? X* x = new X[10]; // (1) delete[] x; // (2) I know that memory leaks are prevented, but additionally: Ad (1), are the previously constructed elements destructed? If yes, what happens if destructor throws in such a case? Ad (2), are the not-yet-destructed elements destructed? If yes, what happens if destructor throws again? 回答1: Yes, if the constructor of x[5] throws, then the five array elements x

问题 So I have done some reading on the new.target boolean added in Node 6.x. Here is a simple example of new.target provided on MDN function Foo() { if (!new.target) throw "Foo() must be called with new"; console.log("Foo instantiated with new"); } Foo(); // throws "Foo() must be called with new" new Foo(); // logs "Foo instantiated with new" But this reads a lot like what I am presently using the below code for var Foo = function (options) { if (!(this instanceof Foo)) { return new Foo(options);

问题 I'm using a QGraphicsScene widget and showing upon it some points as QGraphicsRectItem . This means calling lots of new + addItem() when showing up, and removeItem() + delete to get rid of unused points. Of course, for performance issues, I've implemented my own new and delete operators, which basically recycle pre-allocated memory chunks. Those operators works very well with anything, except for Qt classes (I mean QObject derived classes). The error raised is different every time but always

问题 I have stumbled accross a strange problem in which I cannot understand. I am not an expert at C/C++ so bear with me. I have an NPC class, which derives from a Player class, which derives from a Sprite class. The sprite class contains a setupAnimation function, which allocates an array of floats containing coordinates on the texture, each element of the array refers to a frame of animation. This is all good and works fine. However, a problem occurs when I add an array of pointers to the NPC

问题 I have stumbled accross a strange problem in which I cannot understand. I am not an expert at C/C++ so bear with me. I have an NPC class, which derives from a Player class, which derives from a Sprite class. The sprite class contains a setupAnimation function, which allocates an array of floats containing coordinates on the texture, each element of the array refers to a frame of animation. This is all good and works fine. However, a problem occurs when I add an array of pointers to the NPC

问题 I have the following code : struct foo {}; void bar(foo *d) { new(d) foo(*d); } Does the expression new(d) foo(*d) leave the object pointed to by d unchanged? More specifically, is the above true if the class foo and all the objects contained recursively within it only have trivial copy constructors, then does new(d) foo(*d) leave *d unchanged? A situation in which that is not true could be, new first zeroes out the memory before calling the copy constructor. Are there such clauses in the C++

问题 I ask this question as I have noticed that alot of OpenSource Erlang projects use "new" to pass parameters to Erlang modules, yet I hear at the same time that "new" is not part of the official language and may not be supported if it contains bugs. Before I use it in my own project I would like to clarify this issue. Update: I have since asked on the official Erlang mailing list for an answer: http://www.erlang.org/cgi-bin/ezmlm-cgi?4:mss:49535:201002:aicfhmngkhodmclhlnak 回答1: There is no

问题 Say we create a Function named 'Shape', and add a property 'name' & method 'toString' on it's prototype: var Shape = function () {}; Shape.prototype.name = 'Shape'; Shape.prototype.toString = function () { return this.name; } console.log(Shape.name); // '' console.log(Shape.toString()); // function () {} var Triangle = new Shape(); console.log(Triangle.name); // 'Shape' console.log(Triangle.toString()); // 'Shape' 'NEW' operator did two things: 1. It points this to 'Triangle' 2. It points

问题 I run the following code on VS2005: #include <iostream> #include <string> #include <new> #include <stdlib.h> int flag = 0; void* my_alloc(std::size_t size) { flag = 1; return malloc(size); } void* operator new(std::size_t size) { return my_alloc(size); } void operator delete(void* ptr) { free(ptr); } void* operator new[](std::size_t size) { return my_alloc(size); } void operator delete[](void* ptr) { free(ptr); } int main() { std::string str; std::getline(std::cin, str); std::cout << str;

问题 I was trying to change a ListNode struct into a class format but am running into some issues when testing it. Getting a.out(7016) malloc: * error for object 0x7fff65333b10: pointer being freed was not allocated * set a breakpoint in malloc_error_break to debug chainLink.hpp #ifndef CHAINLINK_H #define CHAINLINK_H using namespace std; #include <iostream> #include <cstdlib> template <typename Object> class chainLink { private: Object storedValue; chainLink *nextLink; public: //Constructor