C++转C#调用ReadProcessMemory传入GameVector结构体报错如何解决

问题原因 #

你当前报错的核心原因有两点：

1. 你当前定义的ReadProcessMemory的P/Invoke签名第三个参数类型为byte[]，无法直接接收自定义的GameVector结构体
2. C#中值类型默认是传值逻辑，你要修改外部传入的vecInfo需要加ref修饰，对应C++的引用传递逻辑

解决方案 #

方案1（推荐，最简洁）：新增适配结构体的P/Invoke重载

首先给GameVector结构体加内存布局控制特性，保证和C++侧布局完全一致：

[StructLayout(LayoutKind.Sequential)] // 强制按定义顺序排布字段内存，避免C#自动调整偏移
struct GameVector
{
    float x, z, y;

    public static GameVector operator +(GameVector ImpliedObject, GameVector vSome)
    {
        return new GameVector() { x = ImpliedObject.x + vSome.x, z = vSome.z, y = ImpliedObject.y + vSome.y };
    }

    public static GameVector operator -(GameVector ImpliedObject, GameVector vSome)
    {
        return new GameVector() { x = ImpliedObject.x - vSome.x, z = ImpliedObject.z, y = ImpliedObject.y - vSome.y };
    }
}

新增ReadProcessMemory的重载签名，直接适配结构体读取：

[DllImport("kernel32.dll")]
static extern bool ReadProcessMemory
(
    IntPtr hProcess, 
    IntPtr lpBaseAddress, 
    out GameVector lpBuffer, 
    int nSize, 
    IntPtr lpNumberOfBytesRead
);

修改GetSpawnPosition方法：

private unsafe void GetSpawnPosition(GameInfo gInfo, ref GameVector vecInfo)
{
    if (!ReadProcessMemory(gInfo.hProc, (IntPtr)(gInfo.dwUnityPlayer + m_vecSpawn), out vecInfo, sizeof(GameVector), IntPtr.Zero))
    {
        Console.WriteLine("Couldnt read spawn cords!");
        return; // 原代码的break语法错误，无外层循环时不能在if块内使用break
    }
}

方案2：复用现有byte[]类型的P/Invoke签名，读完字节数组再转结构体

如果不想新增P/Invoke重载，可以先读入字节数组，再手动反序列化为结构体：
首先实现字节数组转结构体的通用方法：

public static T BytesToStruct<T>(byte[] bytes) where T : struct
{
    int structSize = Marshal.SizeOf<T>();
    IntPtr allocPtr = Marshal.AllocHGlobal(structSize);
    try
    {
        Marshal.Copy(bytes, 0, allocPtr, structSize);
        return Marshal.PtrToStructure<T>(allocPtr);
    }
    finally
    {
        Marshal.FreeHGlobal(allocPtr);
    }
}

修改GetSpawnPosition方法：

private unsafe void GetSpawnPosition(GameInfo gInfo, ref GameVector vecInfo)
{
    byte[] buffer = new byte[sizeof(GameVector)];
    if (!ReadProcessMemory(gInfo.hProc, (IntPtr)(gInfo.dwUnityPlayer + m_vecSpawn), buffer, buffer.Length, out _))
    {
        Console.WriteLine("Couldnt read spawn cords!");
        return;
    }
    vecInfo = BytesToStruct<GameVector>(buffer);
}

内容的提问来源于stack exchange，提问作者Baseult