Hi,
I am not familiar with the .NET wrapper or C#, but in C, fixed length
strings should be represented in memory as character arrays instead of
char *'s. So assuming this translates to C#/.NET, either the struct
should change to something like:
public struct struct1 {
public char measurand[length];
public float rate;
}
Or use a variable-length string in the datatype definition, i.e.
H5T.setSize(stringID, H5T_VARIABLE);. Fixed length strings will have
better performance and can be compressed, while variable length strings
may be more flexible.
I hope this is helpful.
Thanks,
-Neil
On 02/10/2011 09:21 AM, npike wrote:
Hello all,
I am trying to create a Table of CompoundData type that contains both
strings and floats with the C# wrapper, but having great difficulty. In the
example code below, I am trying to insert a single row with 2 columns, the
first one being a string, and the second one being a float.
The float always comes through just fine, but the value in the string cell
always ends up being a symbol. I am using HDFView to look at my h5 files.
What am I doing wrong?
[StructLayout(LayoutKind.Sequential, Pack=1)]
public struct struct1 {
public char* measurand;
public float rate;
}
public static void Main(string[] args){
FileInfo h5 = new FileInfo("myCSharp.h5");
if (h5.Exists) {
h5.Delete();
}
H5FileId fileId = H5F.create("myCSharp.h5",
H5F.CreateMode.ACC_TRUNC);
H5F.close(fileId);
fileId = H5F.open("myCSharp.h5",
H5F.OpenMode.ACC_RDWR);
string test = "foo";
uint len = (uint)test.Length+1;
H5DataTypeId stringID = H5T.copy(H5T.H5Type.C_S1);
H5T.setSize(stringID, len);
H5DataTypeId tid1 =
H5T.create(H5T.CreateClass.COMPOUND,(uint)System.Runtime.InteropServices.Marshal.SizeOf(typeof(struct1)));
H5T.insert(tid1, "Measurand", 0, stringID);
H5T.insert(tid1, "Rate", len, H5T.H5Type.NATIVE_FLOAT);
const int DATA_ARRAY_LENGTH = 12;
// Rank is the number of dimensions of the data array.
const int RANK = 1;
ulong[] attributeDims = new ulong[RANK];
attributeDims[0] = DATA_ARRAY_LENGTH;
H5DataSpaceId spaceId = H5S.create_simple(RANK, attributeDims);
H5DataSetId dataSetId = H5D.create(fileId, "/dictionaries",
tid1, spaceId);
struct1[] dset_data = new struct1[DATA_ARRAY_LENGTH];
struct1 foo = new struct1();
foo.measurand = test;
foo.rate = 125.0f;
byte[] bytes = StructureToByteArray(foo);
GCHandle pinnedPacket = GCHandle.Alloc(bytes, GCHandleType.Pinned);
struct1 msg = (struct1)Marshal.PtrToStructure(
pinnedPacket.AddrOfPinnedObject(),
typeof(struct1));
pinnedPacket.Free();
Console.WriteLine(msg.measurand);
unsafe
{
IntPtr ipp =
System.Runtime.InteropServices.Marshal.StringToHGlobalAnsi(test);
dset_data[0].measurand = (char*)ipp;
dset_data[0].rate = 125.0f;
}
H5D.write(dataSetId, tid1,
new H5Array<struct1>(dset_data));
H5F.close(fileId);
}
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