Question

我正在尝试从C＃结构转储数据，然后将数据加载到VB6结构。这是当前的代码： C＃

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.IO;

namespace MarshalTest
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
        public struct myStruct
        {
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 5)]
            public string str;
            [MarshalAs(UnmanagedType.I4)]
            public int integer; // VB6 long
            [MarshalAs(UnmanagedType.I2)]
            public Int16 int16; // VB6 Integer
            [MarshalAs(UnmanagedType.I1)]
            public byte b;
            [MarshalAs(UnmanagedType.VariantBool)]
            public bool flag;

        }

        private void button1_Click(object sender, EventArgs e)
        {
            myStruct strc = new myStruct();
            //String.Format("{0,6}", strc.str);
            strc.str = "Abhi";
            strc.integer = 49125071;
            strc.int16 = 0491;
            strc.b = 4;
            strc.flag = true;
            Type outputType = typeof(myStruct).IsEnum ? Enum.GetUnderlyingType(typeof(myStruct)) : typeof(myStruct);

            byte[] bArr = new byte[Marshal.SizeOf(strc)];
            IntPtr ptr = IntPtr.Zero;
            try
            {
                ptr = Marshal.AllocHGlobal(Marshal.SizeOf(strc));
                Marshal.StructureToPtr(strc, ptr, false);
                Marshal.Copy(ptr, bArr, 0, Marshal.SizeOf(strc));

                using (FileStream fs =  File.Create("C:\\users\\abhijeet\\desktop\\data.dat"))
                {
                    fs.Write(bArr, 0, bArr.Length);
                    fs.Close();
                }

                // WM_APP is 0x8000
                //IntPtr retval = SendMessage(m_HostWindow, 0x8000, IntPtr.Zero, ptr);
            }
            finally
            {
                if (ptr != IntPtr.Zero)
                {
                    Marshal.DestroyStructure(ptr, typeof(myStruct));
                    Marshal.FreeHGlobal(ptr);
                }
            }
        }

        private string checkFixedLength(string str, int length)
        {
            if (str.Length > length)
            {
                return str.Substring(0, length); 
            }
            return str;
        }

    }
}

VB6

Option Explicit
'Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal ByteLen As Long)
Private Declare Function GetProcessHeap Lib "kernel32" () As Long
Private Declare Function HeapAlloc Lib "kernel32" (ByVal hHeap As Long, ByVal dwFlags As Long, ByVal dwBytes As Long) As Long
Private Declare Function HeapFree Lib "kernel32" (ByVal hHeap As Long, ByVal dwFlags As Long, lpMem As Any) As Long

私有声明子CopyMemory Lib“kernel32”别名“RtlMoveMemory”（目标为任意，源为任意，ByVal长度为长） str As String 我很久我作为整数 b作为字节 flag as Boolean 结束类型

Private Sub cmdCommand1_Click()
    Dim t As myType, f As Long
    Dim bArr() As Byte

    Debug.Print LenB(t)

    ReDim bArr(LenB(t) - 1)
    f = FreeFile
    Open "c:\users\abhijeet\desktop\data.dat" For Binary As #f
    Get #f, , bArr()
    Close #f

    Dim ptr As Long, hHeap As Long
    hHeap = GetProcessHeap
    ptr = HeapAlloc(hHeap, 0, LenB(t))

    CopyMemory ByVal VarPtr(t), ByVal VarPtr(bArr(0)), LenB(t)

    Debug.Print t.str
    Debug.Print t.l
    Debug.Print t.i
    Debug.Print t.b
    Debug.Print t.flag
End Sub

由于某种原因，即使已设置大小常量，结构的大小也总是返回16。我错过了结构的东西吗？

由于

Answer 1

结构大小不包括字符串内容，除非它是固定大小而不是指针。

[MarshalAs(UnmanagedType.ByValTStr, SizeConst=6)]
public string str;

（请注意，documentation for ByValTStr表示它与Vb6的区别在于null终结符）

在VB6方面，您还需要使其成为固定长度的字符串以包含内联内容

str As String * 6

C＃结构为VB6，反之亦然

1 个答案: