将对象转换为char *以保存/加载 [英] Casting an Object to char* for saving/loading

问题描述

我有一个小问题。

我正在写一个加载/保存函数，用于从保存的文件获取平面几何数据。所涉及的对象是从其中具有大量数据的类实例化的，但是它们仅使用简单的旧数据，并且没有指针/分配的存储器等。

I'm writing a loading/saving function for getting plain geometry data from a saved file. The objects involved are instanced from classes with a lot of data in them, but they all use just plain old data, and no pointers/allocated memory and the like.

它可以加载文件到一个分配的char *数组，类型转换，说，几何*，并且安全地期望一切都不扰乱，假设我做了相同的反向的事情保存（typecasting数组到char *，并写它文件）？

Is it possible to load the file into an allocated char* array, typecast that to, say, Geometry* , and safely expect everything to not get scrambled assuming I did the same reversed thing when saving (typecasting the array to char* and writing it to file)?

如果我试图访问数组，当它指向一个char *指针，或一个int *或任何其他指针类型，

If I attempt to access the array when it is pointed to by a char* pointer, or a int*, or any other pointer type, is there any special considerations I need to take?

推荐答案

是否可以将文件加载到
一个分配的char *数组，typecast
，例如，Geometry *

Is it possible to load the file into an allocated char* array, typecast that to, say, Geometry*

这是可能的。我做了一个类似的工作。我使用两个链 static_cast 来执行此操作：

It's possible. I've done a similar job. I had used two chained static_cast to do this, as:

char *buffer;
//..
Geometry *g = static_cast<Geometry *>(static_cast<void*>(buffer));

//reverse
buffer = static_cast<char*>(static_cast<void*>(g));

由于两个链接 static_cast 看起来很麻烦，我写了这个函数模板：

Since the two chained static_cast looks cumbersome, I've written this function template:

template<class To, class From>
To any_cast(From v)
{
    return static_cast<To>(static_cast<void*>(v));
}

然后使用它，

Geometry *g = any_cast<Geometry *>(buffer);

//reverse
buffer = any_cast<char*>(g);

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See this topic:

为什么我们在C ++中有两个链接的static_cast可以完成它的工作？

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