.Net如何调用非托管代码（DLL)

        /// <summary>
        ///
        /// </summary>
        /// <param name="inptr"></param>
        /// <param name="outptr"></param>
        /// <returns></returns>
        [DllImport("Test.DLL", EntryPoint = "TestMethod")]
        public static extern int Kc_BankDataExchg(Up inptr, out Down outptr);

其中Test.dll为动态库名称，TestMethod为动态库内的方法名，inptr为输入结构体，outptr为输出结构体
// 中间件上传结构
    public struct Up
    {
        //通讯码
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 5)]
        public string TransCode;

        //上传文件大小
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 13)]
        public string SizeOfFile;

        //上传文件名
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 65)]
        public string FileName;
    }

    // 中间件下传结构
    public struct Down
    {
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 5)]
        //返回结果码
        public string RetValue;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 65)]
        //下传文件名称
        public string RetFileName;
        //下传文件记录数
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 7)]
        public string RetRowsCount;
    }

string 与非托管中的C++代码对应的为Char型