C＃轉換為VB6，反之亦然

Question

我試圖從C＃結構中轉儲數據，然后將數據加載到VB6結構中。 這是當前代碼：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

私有聲明子CopyMemory庫“ kernel32”別名“ RtlMoveMemory”（目標為任意，源​​為任意，ByVal長度為長）str作為字符串l作為長值i作為整數b作為字節標志作為布爾型結束類型

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

由於某種原因，即使已設置大小常數，結構的大小也始終返回16。 我在結構上缺少什么嗎？

謝謝

Answer 1

除非它是固定大小而不是指針，否則結構大小將不包括字符串內容。

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

（請注意， ByValTStr的文檔說它與帶有空終止符的Vb6不同）

在VB6方面，您還需要使其成為固定長度的字符串以包含內聯內容

str As String * 6