有没有办法将在流或数组上收集的数据映射到数据结构，反之亦然？ 在 C++ 中，这只是将指向流的指针转换为我想要使用的数据类型的问题（反之亦然） 例如：在 C++ 中
Mystruct * pMyStrct = (Mystruct*)&SomeDataStream;
pMyStrct->Item1 = 25;
int iReadData = pMyStrct->Item2;
显然 C++ 方式是相当不安全的，除非您在读取传入数据时确定流数据的质量，但对于传出数据来说非常快速和容易。
【问题讨论】：
标签： c# c++ data-structures
大多数人使用.NET序列化（有更快的二进制和更慢的XML格式化程序，它们都依赖于反射并且在一定程度上具有版本容错性）
但是，如果您想要最快（不安全）的方式 - 为什么不呢：
写作：
YourStruct o = new YourStruct();
byte[] buffer = new byte[Marshal.SizeOf(typeof(YourStruct))];
GCHandle handle = GCHandle.Alloc(buffer, GCHandleType.Pinned);
Marshal.StructureToPtr(o, handle.AddrOfPinnedObject(), false);
handle.Free();
阅读：
handle = GCHandle.Alloc(buffer, GCHandleType.Pinned);
o = (YourStruct)Marshal.PtrToStructure(handle.AddrOfPinnedObject(), typeof(YourStruct));
handle.Free();
【讨论】：
如果 lubos hasko 的回答不够安全，还有 really 不安全的方法，使用 C#中的指针。以下是我遇到的一些提示和陷阱：
using System;
using System.Runtime.InteropServices;
using System.IO;
using System.Diagnostics;
// Use LayoutKind.Sequential to prevent the CLR from reordering your fields.
[StructLayout(LayoutKind.Sequential)]
unsafe struct MeshDesc
{
public byte NameLen;
// Here fixed means store the array by value, like in C,
// though C# exposes access to Name as a char*.
// fixed also requires 'unsafe' on the struct definition.
public fixed char Name[16];
// You can include other structs like in C as well.
public Matrix Transform;
public uint VertexCount;
// But not both, you can't store an array of structs.
//public fixed Vector Vertices[512];
}
[StructLayout(LayoutKind.Sequential)]
unsafe struct Matrix
{
public fixed float M[16];
}
// This is how you do unions
[StructLayout(LayoutKind.Explicit)]
unsafe struct Vector
{
[FieldOffset(0)]
public fixed float Items[16];
[FieldOffset(0)]
public float X;
[FieldOffset(4)]
public float Y;
[FieldOffset(8)]
public float Z;
}
class Program
{
unsafe static void Main(string[] args)
{
var mesh = new MeshDesc();
var buffer = new byte[Marshal.SizeOf(mesh)];
// Set where NameLen will be read from.
buffer[0] = 12;
// Use Buffer.BlockCopy to raw copy data across arrays of primitives.
// Note we copy to offset 2 here: char's have alignment of 2, so there is
// a padding byte after NameLen: just like in C.
Buffer.BlockCopy("Hello!".ToCharArray(), 0, buffer, 2, 12);
// Copy data to struct
Read(buffer, out mesh);
// Print the Name we wrote above:
var name = new char[mesh.NameLen];
// Use Marsal.Copy to copy between arrays and pointers to arrays.
unsafe { Marshal.Copy((IntPtr)mesh.Name, name, 0, mesh.NameLen); }
// Note you can also use the String.String(char*) overloads
Console.WriteLine("Name: " + new string(name));
// If Erik Myers likes it...
mesh.VertexCount = 4711;
// Copy data from struct:
// MeshDesc is a struct, and is on the stack, so it's
// memory is effectively pinned by the stack pointer.
// This means '&' is sufficient to get a pointer.
Write(&mesh, buffer);
// Watch for alignment again, and note you have endianess to worry about...
int vc = buffer[100] | (buffer[101] << 8) | (buffer[102] << 16) | (buffer[103] << 24);
Console.WriteLine("VertexCount = " + vc);
}
unsafe static void Write(MeshDesc* pMesh, byte[] buffer)
{
// But byte[] is on the heap, and therefore needs
// to be flagged as pinned so the GC won't try to move it
// from under you - this can be done most efficiently with
// 'fixed', but can also be done with GCHandleType.Pinned.
fixed (byte* pBuffer = buffer)
*(MeshDesc*)pBuffer = *pMesh;
}
unsafe static void Read(byte[] buffer, out MeshDesc mesh)
{
fixed (byte* pBuffer = buffer)
mesh = *(MeshDesc*)pBuffer;
}
}
【讨论】：
如果两边都是.net：
认为您应该使用二进制序列化并发送 byte[] 结果。
相信你的结构是完全可blittable的可能会很麻烦。
您将支付一些开销（CPU 和网络），但会很安全。
【讨论】：
如果您需要手动填充每个成员变量，您可以通过使用 FormatterServices 按顺序检索与对象关联的变量类型列表，就原语而言对其进行概括。我不得不在一个项目中这样做，我有很多不同的消息类型来自流，我绝对不想为每条消息编写序列化器/反序列化器。
这是我用来概括从 byte[] 反序列化的代码。
public virtual bool SetMessageBytes(byte[] message)
{
MemberInfo[] members = FormatterServices.GetSerializableMembers(this.GetType());
object[] values = FormatterServices.GetObjectData(this, members);
int j = 0;
for (int i = 0; i < members.Length; i++)
{
string[] var = members[i].ToString().Split(new char[] { ' ' });
switch (var[0])
{
case "UInt32":
values[i] = (UInt32)((message[j] << 24) + (message[j + 1] << 16) + (message[j + 2] << 8) + message[j + 3]);
j += 4;
break;
case "UInt16":
values[i] = (UInt16)((message[j] << 8) + message[j + 1]);
j += 2;
break;
case "Byte":
values[i] = (byte)message[j++];
break;
case "UInt32[]":
if (values[i] != null)
{
int len = ((UInt32[])values[i]).Length;
byte[] b = new byte[len * 4];
Array.Copy(message, j, b, 0, len * 4);
Array.Copy(Utilities.ByteArrayToUInt32Array(b), (UInt32[])values[i], len);
j += len * 4;
}
break;
case "Byte[]":
if (values[i] != null)
{
int len = ((byte[])values[i]).Length;
Array.Copy(message, j, (byte[])(values[i]), 0, len);
j += len;
}
break;
default:
throw new Exception("ByteExtractable::SetMessageBytes Unsupported Type: " + var[1] + " is of type " + var[0]);
}
}
FormatterServices.PopulateObjectMembers(this, members, values);
return true;
}
【讨论】：