C# wrapper error code 6211

[Takayama]

I am writing a wrapper in C# to read TDM files too.

But I met the error code 6211 using OpenFileEx.

using System.Runtime.InteropServices;

namespace MyTDMSTest_CSharp
{
   class Program
    {
 
        [DllImport("nilibddc.dll")]
        static extern int DDC_OpenFileEx(string filePath, string filetype, int readOnly, out IntPtr pfile);
        [DllImport("nilibddc.dll")]
        static extern string DDC_CloseFile(out IntPtr pfile);
        [DllImport("nilibddc.dll")]
        static extern string DDC_GetLibraryErrorDescription(int errorCode);

        private const string FILE_PATH = "testtdms.tdms";

       static void Main(string[] args)
        {
            int ret;
            IntPtr pfile;

            ret = DDC_OpenFileEx(FILE_PATH, "TDMS", 1, out pfile);
            if (ret < 0)
            {
               string buff = DDC_GetLibraryErrorDescription(ret);
               Console.WriteLine("\nError:{0:D} {1}",ret,buff);
               Console.ReadKey();
            }
            else
            {
               DDC_CloseFile(out pfile);
             }
        }
    }
}

This code shows bellow message.

"Error:-6211 The storage could not be opened."

I'm using VS2010 with Win7(32bit) . 

How to solve this error?

Thanks for any help.

[AndreasK]

I have no real knowledge about C wrapper in c# but I assume string does not work.

I think there must be some kind of Marshaller.

[MarshalAs(UnmanagedType.LPStr)]string filepath

because you have to convert to char*.

[Takayama]

---

Hello Andreask
Thank you for your quick reply.
I have modifed the code.

        [DllImport("nilibddc.dll")]
        static extern int DDC_OpenFileEx(
            [MarshalAs(UnmanagedType.LPStr)]string filePath,
            [MarshalAs(UnmanagedType.LPStr)]string filetype,
            int readOnly,
            out IntPtr pfile);

But that does not work . it shows the same error.

I guess the error code 6211 is caused by pfile because i got other error  "Error:-6209 The file passed to the library does not exist." when i changed the FILEPATH. 

Best regards

---

[StefanR · Accepted solution]

In case you have copied the dlls to a different location, did you also copy the "DataModels" folder?

[Takayama · Accepted solution]

Thank a lot. It is solved !!

using System.Runtime.InteropServices;

namespace MyTDMSTest_CSharp
{
   class Program
    {
 
        [DllImport("nilibddc.dll")]
        static extern int DDC_OpenFileEx(string filePath, string filetype, int readOnly, out IntPtr pfile);
        [DllImport("nilibddc.dll")]
        static extern int DDC_CloseFile(IntPtr pfile);
        [DllImport("nilibddc.dll")]
        static extern string DDC_GetLibraryErrorDescription(int errorCode);
        [DllImport("nilibddc.dll")]
        static extern int DDC_GetFileStringPropertyLength(IntPtr pfile, string property, out int length);
        [DllImport("nilibddc.dll")]
        static extern int DDC_GetFileProperty(
                IntPtr pfile, 
                string property, 
                StringBuilder fileproperty,
                int valueSizeInBytes);

        private const string FILE_PATH = "TdmsSampleData.tdms";
        
        static void Main(string[] args)
        {
            int ret;
            IntPtr pfile;
            int length;

            ret = DDC_OpenFileEx(FILE_PATH, "TDMS", 1, out pfile);
            if (ret < 0) return;
            ret = DDC_GetFileStringPropertyLength(pfile, "name", out length);
            if (ret >= 0)
            {
                StringBuilder buff = new StringBuilder(length);
                ret = DDC_GetFileProperty(pfile, "name", buff, length);
                if (ret < 0)
                {
                    string msg = DDC_GetLibraryErrorDescription(ret);
                    Console.WriteLine("\nError:{0:D} {1}", ret, msg);
                    Console.ReadKey();
                }
                else
                {
                    Console.WriteLine("File name property ({0:D}): {1}", length, buff);
                    Console.WriteLine("End of program, press Enter key to quit");
                    Console.ReadLine();
                }
            }
            ret = DDC_CloseFile(pfile);
        }
    }
}