eccodes/examples/C/bufr_missing.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: bufr_missing
 *
 * Description: how to handle missing values in BUFR messages.
 */

#include "eccodes.h"
#include <assert.h>

int main(int argc, char* argv[])
{
    FILE* in = NULL;

    /* message handle. Required in all the eccodes calls acting on a message.*/
    codes_handle* h = NULL;

    double doubleVal;
    int err            = 0;
    int is_missing     = 0;
    int cnt            = 0;
    const char* infile = "../../data/bufr/syno_1.bufr";

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

    /* loop over the messages in the bufr file */
    while ((h = codes_handle_new_from_file(NULL, in, PRODUCT_BUFR, &err)) != NULL || err != CODES_SUCCESS) {
        if (h == NULL) {
            fprintf(stderr, "Error: unable to create handle for message %d\n", cnt);
            cnt++;
            continue;
        }

        printf("message: %d\n", cnt);

        /* we need to instruct ecCodes to expand the descriptors
          i.e. unpack the data values */
        CODES_CHECK(codes_set_long(h, "unpack", 1), 0);

        /* the value of this key is missing in the message*/
        CODES_CHECK(codes_get_double(h, "relativeHumidity", &doubleVal), 0);

        /* we will print "value missing" */
        if (doubleVal == CODES_MISSING_DOUBLE) {
            printf("   --> value missing\n");
        }
        else {
            printf("   --> value present\n");
        }

        is_missing = codes_is_missing(h, "relativeHumidity", &err);
        assert(!err);
        assert(is_missing == 1);

        /* delete handle */
        codes_handle_delete(h);

        cnt++;
    }

    fclose(in);
    return 0;
}