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Diffstat (limited to 'HDF5Examples/C/H5T/h5ex_t_opaqueatt.c')
-rw-r--r-- | HDF5Examples/C/H5T/h5ex_t_opaqueatt.c | 146 |
1 files changed, 146 insertions, 0 deletions
diff --git a/HDF5Examples/C/H5T/h5ex_t_opaqueatt.c b/HDF5Examples/C/H5T/h5ex_t_opaqueatt.c new file mode 100644 index 0000000..e88031a --- /dev/null +++ b/HDF5Examples/C/H5T/h5ex_t_opaqueatt.c @@ -0,0 +1,146 @@ +/************************************************************ + + This example shows how to read and write opaque datatypes + to an attribute. The program first writes opaque data 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. + + ************************************************************/ + +#include "hdf5.h" +#include <stdio.h> +#include <stdlib.h> + +#define FILE "h5ex_t_opaqueatt.h5" +#define DATASET "DS1" +#define ATTRIBUTE "A1" +#define DIM0 4 +#define LEN 7 + +int +main(void) +{ + hid_t file, space, dtype, dset, attr; /* Handles */ + herr_t status; + hsize_t dims[1] = {DIM0}; + size_t len; + char wdata[DIM0 * LEN], /* Write buffer */ + *rdata, /* Read buffer */ + str[LEN] = "OPAQUE", *tag; + int ndims; + hsize_t i, j; + + /* + * Initialize data. + */ + for (i = 0; i < DIM0; i++) { + for (j = 0; j < LEN - 1; j++) + wdata[j + i * LEN] = str[j]; + wdata[LEN - 1 + i * LEN] = (char)i + '0'; + } + + /* + * Create a new file using the default properties. + */ + file = H5Fcreate(FILE, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT); + + /* + * 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 opaque datatype and set the tag to something appropriate. + * For this example we will write and view the data as a character + * array. + */ + dtype = H5Tcreate(H5T_OPAQUE, LEN); + status = H5Tset_tag(dtype, "Character array"); + + /* + * 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 opaque data to it. + */ + attr = H5Acreate(dset, ATTRIBUTE, dtype, space, H5P_DEFAULT, H5P_DEFAULT); + status = H5Awrite(attr, dtype, wdata); + + /* + * Close and release resources. + */ + status = H5Aclose(attr); + status = H5Dclose(dset); + status = H5Sclose(space); + status = H5Tclose(dtype); + 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 datatype and properties for the datatype. Note that H5Tget_tag + * allocates space for the string in tag, so we must remember to release it + * later. + */ + dtype = H5Aget_type(attr); + len = H5Tget_size(dtype); + tag = H5Tget_tag(dtype); + + /* + * 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] * len); + + /* + * Read the data. + */ + status = H5Aread(attr, dtype, rdata); + + /* + * Output the data to the screen. + */ + printf("Datatype tag for %s is: \"%s\"\n", ATTRIBUTE, tag); + for (i = 0; i < dims[0]; i++) { + printf("%s[%llu]: ", ATTRIBUTE, i); + for (j = 0; j < len; j++) + printf("%c", rdata[j + i * len]); + printf("\n"); + } + + /* + * Close and release resources. + */ + free(rdata); +#if H5_VERSION_GE(1, 10, 0) && !defined(H5_USE_18_API) && !defined(H5_USE_16_API) + H5free_memory(tag); +#else + free(tag); +#endif + status = H5Aclose(attr); + status = H5Dclose(dset); + status = H5Sclose(space); + status = H5Tclose(dtype); + status = H5Fclose(file); + + return 0; +} |