c# - 在 C# 中移动结构数据

Question

假设我在 C 中有以下结构

typedef struct
{
    int field1;
    char field2[16];
} MYSTRUCT;

现在我有一个用指向 MYSTRUCT 的指针调用的 C 例程，我需要填充该结构，例如，

int MyCall(MYSTRUCT *ms)
{
    char *hello = "hello world";
    int hlen = strlen(hello);
    ms->field1 = hlen;
    strcpy_s(ms->field2,16,hello);
    return(hlen);
}

如何用 C# 编写 MyCall？我在 Visual Studio 2010 中试过这个:

...
using System.Runtime.InteropServices;
[StructLayout(LayoutKind.Explicit)]
public struct MYSTRUCT
{
    [FieldOffset(0)]
    UInt32 field1;
    [FieldOffset(4)]
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 16)]
    string field2;
}

public int MyProc(ref MYSTRUCT ms)
{
    string hello = "hello world";
    int hlen = hello.Length;
    Marshal.Copy(hello, ms.field2, 0, hlen); // doesn't work
    Array.Copy(hello, ms.field2, hlen);      // doesn't work
    // tried a number of other ways with no luck
    // ms.field2 is not a resolved reference
    return(hlen);
}

感谢您提供有关正确执行此操作的任何提示。

Answer 1

尝试更改 StructLayout。

[StructLayout(LayoutKind.Sequential, CharSet=CharSet.Unicode)]
public struct MYSTRUCT
{
    public UInt32 field1;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 16)]
    public string field2;
}

既然您是作为引用传递的，您是否尝试过将其设置为:

public int MyProc(ref MYSTRUCT ms)
{
    string hello = "hello world";
    ms.field2 = hello;
    return hello.Length;
}

当使用 ref 关键字时，您将像这样调用 MyProc:

static void Main(string[] args)
{
    var s = new MYSTRUCT();
    Console.WriteLine(MyProc(ref s)); // you must use "ref" when passing an argument
    Console.WriteLine(s.field2);
    Console.ReadKey();
}