如何在已分配的内存上调用构造函数？ [英] How to call a constructor on an already allocated memory?

问题描述

如何在已经分配的内存区域上调用构造函数？

How can I call a constructor on a memory region that is already allocated?

推荐答案

您可以使用放置新的构造函数

You can use the placement new constructor, which takes an address.

Foo* foo = new (your_memory_address_here) Foo ();

在 C ++常见问题精简版或 MSDN 。您唯一需要确保内存正确对齐的内容（ malloc 应该返回适​​合任何内容的内存，但是要提防可能需要使用SSE之类的东西对齐到16个字节左右的边界）。

Take a look at a more detailed explanation at the C++ FAQ lite or the MSDN. The only thing you need to make sure that the memory is properly aligned (malloc is supposed to return memory that is properly aligned for anything, but beware of things like SSE which may need alignment to 16 bytes boundaries or so).

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