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+/************************************************************
+
+ This example shows how to read and write variable-length
+ string datatypes to an attribute. The program first
+ writes variable-length strings to an attribute with a
+ dataspace of DIM0, then closes the file. Next, it reopens
+ the file, reads back the data, and outputs it to the
+ screen.
+
+ This file is intended for use with HDF5 Library version 1.8
+
+ ************************************************************/
+
+#include "hdf5.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+#define FILE "h5ex_t_vlstringatt.h5"
+#define DATASET "DS1"
+#define ATTRIBUTE "A1"
+#define DIM0 4
+
+int
+main(void)
+{
+ hid_t file, filetype, memtype, space, dset, attr;
+ /* Handles */
+ herr_t status;
+ hsize_t dims[1] = {DIM0};
+ char *wdata[DIM0] = {"Parting", "is such", "sweet", "sorrow."},
+ /* Write buffer */
+ **rdata; /* Read buffer */
+ int ndims, i;
+
+ /*
+ * Create a new file using the default properties.
+ */
+ file = H5Fcreate(FILE, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
+
+ /*
+ * Create file and memory datatypes. For this example we will save
+ * the strings as FORTRAN strings.
+ */
+ filetype = H5Tcopy(H5T_FORTRAN_S1);
+ status = H5Tset_size(filetype, H5T_VARIABLE);
+ memtype = H5Tcopy(H5T_C_S1);
+ status = H5Tset_size(memtype, H5T_VARIABLE);
+
+ /*
+ * Create dataset with a null dataspace.
+ */
+ space = H5Screate(H5S_NULL);
+ dset = H5Dcreate(file, DATASET, H5T_STD_I32LE, space, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+ status = H5Sclose(space);
+
+ /*
+ * Create dataspace. Setting maximum size to NULL sets the maximum
+ * size to be the current size.
+ */
+ space = H5Screate_simple(1, dims, NULL);
+
+ /*
+ * Create the attribute and write the variable-length string data
+ * to it.
+ */
+ attr = H5Acreate(dset, ATTRIBUTE, filetype, space, H5P_DEFAULT, H5P_DEFAULT);
+ status = H5Awrite(attr, memtype, wdata);
+
+ /*
+ * Close and release resources.
+ */
+ status = H5Aclose(attr);
+ status = H5Dclose(dset);
+ status = H5Sclose(space);
+ status = H5Tclose(filetype);
+ status = H5Tclose(memtype);
+ status = H5Fclose(file);
+
+ /*
+ * Now we begin the read section of this example. Here we assume
+ * the attribute has the same name and rank, but can have any size.
+ * Therefore we must allocate a new array to read in data using
+ * malloc().
+ */
+
+ /*
+ * Open file, dataset, and attribute.
+ */
+ file = H5Fopen(FILE, H5F_ACC_RDONLY, H5P_DEFAULT);
+ dset = H5Dopen(file, DATASET, H5P_DEFAULT);
+ attr = H5Aopen(dset, ATTRIBUTE, H5P_DEFAULT);
+
+ /*
+ * Get the datatype.
+ */
+ filetype = H5Aget_type(attr);
+
+ /*
+ * Get dataspace and allocate memory for read buffer.
+ */
+ space = H5Aget_space(attr);
+ ndims = H5Sget_simple_extent_dims(space, dims, NULL);
+ rdata = (char **)malloc(dims[0] * sizeof(char *));
+
+ /*
+ * Create the memory datatype.
+ */
+ memtype = H5Tcopy(H5T_C_S1);
+ status = H5Tset_size(memtype, H5T_VARIABLE);
+
+ /*
+ * Read the data.
+ */
+ status = H5Aread(attr, memtype, rdata);
+
+ /*
+ * Output the data to the screen.
+ */
+ for (i = 0; i < dims[0]; i++)
+ printf("%s[%d]: %s\n", ATTRIBUTE, i, rdata[i]);
+
+ /*
+ * Close and release resources. Note that H5Dvlen_reclaim works
+ * for variable-length strings as well as variable-length arrays.
+ * Also note that we must still free the array of pointers stored
+ * in rdata, as H5Tvlen_reclaim only frees the data these point to.
+ */
+ status = H5Dvlen_reclaim(memtype, space, H5P_DEFAULT, rdata);
+ free(rdata);
+ status = H5Aclose(attr);
+ status = H5Dclose(dset);
+ status = H5Sclose(space);
+ status = H5Tclose(filetype);
+ status = H5Tclose(memtype);
+ status = H5Fclose(file);
+
+ return 0;
+}