类和结构的内部存储
我想使用指针 magikry 来保存 C++ 类，使用以下将字节数据写入文件的方法：
result Osp::Io::File::Write (const void *buffer, int length);
参数：
buffer— 指向用户提供的缓冲区的指针，其中包含要写入的字节数据length— 缓冲区长度（以字节为单位）
例外：< /p>
E_SUCCESS— 该方法成功。E_INVALID_STATE— 文件尚未打开。E_ILLEGAL_ACCESS— 文件未打开进行写入操作，或由于权限不足而拒绝访问。E_INVALID_ARG— 发生了以下任一情况：- 指定的缓冲区包含空指针。
- 指定的缓冲区长度等于或小于0。
- 文件句柄无效（文件被其他方法关闭，或者内存已损坏）。
E_STORAGE_FULL— 磁盘空间已满。E_IO— 由于介质突然弹出或检测到文件损坏，发生了意外的设备故障。
我宁愿不假设会有任何类型的缓冲，尽管我相信每个字节不会导致整个闪存块被重写，但我想知道是否有一种更好的方法来写入所有数据字段例如，通过指向对象的指针 (*this) 来创建类（没有其他内容，例如静态字段）？
I want to use pointer magikry to save a C++ class using the following method that writes byte data into a file:
result Osp::Io::File::Write (const void *buffer, int length);
Parameters:
buffer— A pointer to the user-supplied buffer that contains byte data to be writtenlength— The buffer length in bytes
Exceptions:
E_SUCCESS— The method is successful.E_INVALID_STATE— The file has not been opened as yet.E_ILLEGAL_ACCESS— The file is not opened for write operation, or access is denied due to insufficient permission.E_INVALID_ARG— Either of the following conditions has occurred:- The specified buffer contains a null pointer.
- The specified buffer length is equal or smaller than 0.
- The file handle is invalid (either the file is closed by another method, or the memory is corrupted).
E_STORAGE_FULL— The disk space is full.E_IO— An unexpected device failure has occurred as the media ejected suddenly or file corruption is detected.
I'd rather not assume that there will be any sort of buffering, although I am confident each byte won't occasion a whole block of flash to be rewritten but I was wondering if there is a niftier way to write all the data fields of a class (and nothing else, eg static fields) by, eg, a pointer to the object (*this)?
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在 C++ 中，您不会将“原始”对象写入文件，而是将它们序列化。这并不神奇，您需要自己编写序列化代码（为了方便起见，重载运算符
<<和>>）。您可以通过仅转储内存来实现旧的 C 风格，但除了 C 语言通常会导致的问题（对齐、在系统之间传输数据时的字节序问题）之外，您还会遇到 C++ 引入的问题（内部类表示） ，可能的“隐藏”数据成员，例如v表等）。
如果您想确保读取和写入可以在不同系统和/或不同软件之间传输的可靠数据 - 您最好实现序列化，而不是寻找捷径。
您可以使用 Boost.Serialization 之类的库。
In C++ you don't write "raw" objects into files, but rather serialize them. There's no magic, you need to write your serialization code yourself (overloading operators
<<and>>, for convenience).You can do it the old C-style by just dumping memory, but in addition to the problems this would generally cause with C (alignment, endian issues when transferring data between systems), you also get the problems introduced by C++ (internal class representation, possible "hidden" data members such as a v-table, etc).
If you want to ensure you read and write reliable data that can be transferred between different systems and/or different pieces of software - you better implement the serialization, and don't look for shortcuts.
You can use libraries like Boost.Serialization for that.