p/invoke 的结构变量的内存对齐 - 字符串丢失最后一个字符

我正在尝试通过 P/Invoke 使用 C# 代码中的 btrieve API 从 Btrieve （v6.15） 数据库中读取记录。

我已经设法阅读了记录，但是在阅读时裁剪了字符串的最后一个字符。如果我增加数据结构中的字符串大小，则正确读取字符串，但这次未正确读取下一个变量。

这里可能出了什么问题？

Btrieve 函数声明：

        [DllImport("WBTRV32.dll", CharSet = CharSet.Ansi)]
    static extern short BTRCALL(ushort operation,
        [MarshalAs(UnmanagedType.LPArray, SizeConst = 128)] byte[] posBlk,
        [MarshalAs(UnmanagedType.Struct, SizeConst = 255)] 
        ref RecordBuffer databuffer, 
        ref int dataLength, 
        [MarshalAs(UnmanagedType.LPArray, SizeConst = 255)] char[] keyBffer, 
        ushort keyLength, ushort keyNum);

我的结构定义：

    [StructLayout(LayoutKind.Sequential, Pack = 1, CharSet = CharSet.Ansi)]
    public struct RecordBuffer
    {
        public short docType;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 15)]
        public string docDescPlural;
        public short sorting;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 15)]
        public string docDescSingle;
        public short copyOtherThanSrc;
        public double defaultNotebookNo;
    }

以下是来自 Btreive 数据库管理器的列的大小：

1. 有符号整数，2 字节
2. 字符串，15 字节
3. 有符号整数，2 字节
4. 字符串，15 字节
5. 有符号整数，2 字节
6. 浮点型，8 字节

代码：

    private void PopulateAllRecords(string fileName)
    {
        byte[] positionBlock = new byte[128];
        char[] fileNameArray = fileName.ToCharArray();
        // Open file
        RecordBuffer dataBuffer = new RecordBuffer();
        int bufferLength = System.Runtime.InteropServices.Marshal.SizeOf(dataBuffer);
        BReturnCodes status = (BReturnCodes) BTRCALL(
            BOPEN, positionBlock, ref dataBuffer, ref bufferLength, fileNameArray, 0, 0);
        if (status == BReturnCodes.NO_ERROR)
        {
            // Get first record
            dataBuffer = new RecordBuffer();
            status = (BReturnCodes) BTRCALL(
                BGETFIRST, positionBlock, ref dataBuffer, ref bufferLength, fileNameArray, 0, 0);
            if (status == BReturnCodes.NO_ERROR)
            {
                AddListViewItem(dataBuffer);
            }
            // Get subsequent records
            while (status == BReturnCodes.NO_ERROR) // BReturnCodes.END_OF_FILE or an error will occur
            {
                dataBuffer = new RecordBuffer();
                status = (BReturnCodes)BTRCALL(
                    BGETNEXT, positionBlock, ref dataBuffer, ref bufferLength, fileNameArray, 0, 0);
                if (status == BReturnCodes.NO_ERROR)
                {
                    AddListViewItem(dataBuffer);                        
                }
            }
        }
        else
        {
            MessageBox.Show("Error occured while opening file: " + status.ToString());
        }
    }
    private void AddListViewItem(RecordBuffer buffer)
    {
        ListViewItem item = new ListViewItem(buffer.docType.ToString());
        item.SubItems.Add(buffer.docDescPlural);
        item.SubItems.Add(buffer.sorting.ToString());
        item.SubItems.Add(buffer.docDescSingle);
        item.SubItems.Add(buffer.copyOtherThanSrc.ToString());
        item.SubItems.Add(buffer.defaultNotebookNo.ToString());
        listView.Items.Add(item);
    }

编辑：将字符串更改为字符数组（感谢weismat的回答）解决了问题。快乐！

    [StructLayout(LayoutKind.Sequential, Pack = 1, CharSet = CharSet.Ansi)]
    public struct RecordBuffer
    {
        public short docType;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 15)]
        public char[] docDescPlural;
        public short sorting;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 15)]
        public char[] docDescSingle;
        public short copyOtherThanSrc;
        public double defaultNotebookNo;
    }