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author | Allen Byrne <50328838+byrnHDF@users.noreply.github.com> | 2023-11-27 21:30:15 (GMT) |
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committer | GitHub <noreply@github.com> | 2023-11-27 21:30:15 (GMT) |
commit | fc88fcde1091cf12c1e88c783a14ee0f1cffe31c (patch) | |
tree | 91b88b62cd30ed37ee9227e43989e95035be43c3 /HDF5Examples/C/H5T/h5ex_t_vlen.c | |
parent | a067bf71f57723d2dfca7dfe2ffd9ea502eccd4f (diff) | |
download | hdf5-fc88fcde1091cf12c1e88c783a14ee0f1cffe31c.zip hdf5-fc88fcde1091cf12c1e88c783a14ee0f1cffe31c.tar.gz hdf5-fc88fcde1091cf12c1e88c783a14ee0f1cffe31c.tar.bz2 |
Develop merge examples (#3851)
* Merge examples repo into library
* Change grepTest to be more fault-tolerant
* Update examples macro file
* Exclude all Fortran examples from doxygen
Diffstat (limited to 'HDF5Examples/C/H5T/h5ex_t_vlen.c')
-rw-r--r-- | HDF5Examples/C/H5T/h5ex_t_vlen.c | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/HDF5Examples/C/H5T/h5ex_t_vlen.c b/HDF5Examples/C/H5T/h5ex_t_vlen.c new file mode 100644 index 0000000..7111a34 --- /dev/null +++ b/HDF5Examples/C/H5T/h5ex_t_vlen.c @@ -0,0 +1,144 @@ +/************************************************************ + + This example shows how to read and write variable-length + datatypes to a dataset. The program first writes two + variable-length integer arrays to a dataset 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_vlen.h5" +#define DATASET "DS1" +#define LEN0 3 +#define LEN1 12 + +int +main(void) +{ + hid_t file, filetype, memtype, space, dset; + /* Handles */ + herr_t status; + hvl_t wdata[2], /* Array of vlen structures */ + *rdata; /* Pointer to vlen structures */ + hsize_t dims[1] = {2}; + int *ptr, ndims; + hsize_t i, j; + + /* + * Initialize variable-length data. wdata[0] is a countdown of + * length LEN0, wdata[1] is a Fibonacci sequence of length LEN1. + */ + wdata[0].len = LEN0; + ptr = (int *)malloc(wdata[0].len * sizeof(int)); + for (i = 0; i < wdata[0].len; i++) + ptr[i] = wdata[0].len - (size_t)i; /* 3 2 1 */ + wdata[0].p = (void *)ptr; + + wdata[1].len = LEN1; + ptr = (int *)malloc(wdata[1].len * sizeof(int)); + ptr[0] = 1; + ptr[1] = 1; + for (i = 2; i < wdata[1].len; i++) + ptr[i] = ptr[i - 1] + ptr[i - 2]; /* 1 1 2 3 5 8 etc. */ + wdata[1].p = (void *)ptr; + + /* + * Create a new file using the default properties. + */ + file = H5Fcreate(FILE, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT); + + /* + * Create variable-length datatype for file and memory. + */ + filetype = H5Tvlen_create(H5T_STD_I32LE); + memtype = H5Tvlen_create(H5T_NATIVE_INT); + + /* + * Create dataspace. Setting maximum size to NULL sets the maximum + * size to be the current size. + */ + space = H5Screate_simple(1, dims, NULL); + + /* + * Create the dataset and write the variable-length data to it. + */ + dset = H5Dcreate(file, DATASET, filetype, space, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT); + status = H5Dwrite(dset, memtype, H5S_ALL, H5S_ALL, H5P_DEFAULT, wdata); + + /* + * Close and release resources. Note the use of H5Dvlen_reclaim + * removes the need to manually free() the previously malloc'ed + * data. + */ + status = H5Dvlen_reclaim(memtype, space, H5P_DEFAULT, wdata); + 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 dataset 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 and dataset. + */ + file = H5Fopen(FILE, H5F_ACC_RDONLY, H5P_DEFAULT); + dset = H5Dopen(file, DATASET, H5P_DEFAULT); + + /* + * Get dataspace and allocate memory for array of vlen structures. + * This does not actually allocate memory for the vlen data, that + * will be done by the library. + */ + space = H5Dget_space(dset); + ndims = H5Sget_simple_extent_dims(space, dims, NULL); + rdata = (hvl_t *)malloc(dims[0] * sizeof(hvl_t)); + + /* + * Create the memory datatype. + */ + memtype = H5Tvlen_create(H5T_NATIVE_INT); + + /* + * Read the data. + */ + status = H5Dread(dset, memtype, H5S_ALL, H5S_ALL, H5P_DEFAULT, rdata); + + /* + * Output the variable-length data to the screen. + */ + for (i = 0; i < dims[0]; i++) { + printf("%s[%llu]:\n {", DATASET, i); + ptr = rdata[i].p; + for (j = 0; j < rdata[i].len; j++) { + printf(" %d", ptr[j]); + if ((j + 1) < rdata[i].len) + printf(","); + } + printf(" }\n"); + } + + /* + * Close and release resources. Note we must still free the + * top-level pointer "rdata", as H5Dvlen_reclaim only frees the + * actual variable-length data, and not the structures themselves. + */ + status = H5Dvlen_reclaim(memtype, space, H5P_DEFAULT, rdata); + free(rdata); + status = H5Dclose(dset); + status = H5Sclose(space); + status = H5Tclose(memtype); + status = H5Fclose(file); + + return 0; +} |