eccodes/examples/C/grib_set_pv.c

/*
 * (C) Copyright 2005- ECMWF.
 *
 * This software is licensed under the terms of the Apache Licence Version 2.0
 * which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
 *
 * In applying this licence, ECMWF does not waive the privileges and immunities granted to it by
 * virtue of its status as an intergovernmental organisation nor does it submit to any jurisdiction.
 */

/*
 * C Implementation: grib_set_pv
 *
 * Description: how to set pv (vertical coordinate parameters)
 *
 */
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include "eccodes.h"

static void usage(const char* prog)
{
    fprintf(stderr, "usage: %s in out\n", prog);
    exit(1);
}

int main(int argc, char** argv)
{
    int err       = 0;
    long NV       = 0;
    size_t size   = 0;
    double pv[4]  = { 1, 2, 3, 4 };
    size_t pvsize = 4;

    FILE* in           = NULL;
    char* infile       = NULL;
    FILE* out          = NULL;
    char* outfile      = NULL;
    codes_handle* h    = NULL;
    const void* buffer = NULL;

    if (argc != 3) usage(argv[0]);
    infile  = argv[1];
    outfile = argv[2];

    in = fopen(infile, "rb");
    if (!in) {
        fprintf(stderr, "ERROR: unable to open input file %s\n", infile);
        return 1;
    }

    out = fopen(outfile, "wb");
    if (!out) {
        fprintf(stderr, "ERROR: unable to open output file %s\n", outfile);
        fclose(in);
        return 1;
    }

    /* create a new handle from a message in a file */
    h = codes_handle_new_from_file(0, in, PRODUCT_GRIB, &err);
    if (h == NULL) {
        fprintf(stderr, "Error: unable to create handle from file %s\n", infile);
    }

    CODES_CHECK(codes_set_long(h, "PVPresent", 1), 0);

    CODES_CHECK(codes_set_double_array(h, "pv", pv, pvsize), 0);

    /* Once we set the pv array, the NV key should be also set */
    CODES_CHECK(codes_get_long(h, "NV", &NV), 0);
    assert(NV == pvsize);

    /* get the coded message in a buffer */
    CODES_CHECK(codes_get_message(h, &buffer, &size), 0);

    /* write the buffer in a file*/
    if (fwrite(buffer, 1, size, out) != size) {
        perror(argv[1]);
        exit(1);
    }

    codes_handle_delete(h);
    fclose(in);
    fclose(out);

    return 0;
}