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C程序，用一个指向MYSTRUCT的指针调用，我需要填充结构，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);
}

我如何在C＃中编写MyCall？我在Visual Studio 2010中尝试过这个：

...
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方法的任何提示。

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;
}

因为您作为参考传递，您是否尝试将其设置为：

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

使用ref关键字时，您可以这样调用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();
}

在C＃中移动结构数据

1 个答案: