这个new（）语句的说明 [英] Explanation of this new() statement

问题描述

我正在查看一段C ++代码，我来到这个语句块：

I am reviewing a section of C++ code an I came accross this statement block:

static void Vector3DefaultConstructor(Vector3 *self)
{    
    new(self) Vector3();    
}

我之前没有用这种方式使用新的操作符。

I have not come accross the new operator being used in this way before. Can someone explain why new is being called in this way?

推荐答案

这被称为placement new 。默认情况下，它不分配内存，而是在给定位置（这里， self ）构造对象。但

This is called "placement new". By default, it does not allocate memory but instead constructs the object at the given location (here, self). It can, however, be overloaded for a class.

请参阅 FAQ 了解更多信息。

正确的销毁使用放置 new 是通过直接调用析构函数：

The correct way to destroy an object constructed using placement new is by calling the destructor directly:

obj->~Vector3();

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