eccodes/examples/C/grib_list.c

/*
 * Copyright 2005-2019 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_list
 *
 * Description: how to get values using keys.
 *
 */
#include <stdio.h>
#include <assert.h>

#include "eccodes.h"

int main(int argc, char** argv)
{
    int err = 0;

    size_t i = 0;
    size_t count;
    size_t size;

    long numberOfContributingSpectralBands;
    long values[1024];
    long new_values[1024];

    FILE* in = NULL;
    const char* filename = "../../data/satellite.grib";
    codes_handle *h = NULL;

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

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

    CODES_CHECK(codes_get_long(h,"numberOfContributingSpectralBands",&numberOfContributingSpectralBands),0);
    assert(numberOfContributingSpectralBands == 3);

    /* Shrink NB to 2 */
    numberOfContributingSpectralBands = 2;
    CODES_CHECK(codes_set_long(h,"numberOfContributingSpectralBands",numberOfContributingSpectralBands),0);

    /* Expand NB to 9 */
    numberOfContributingSpectralBands = 9;
    CODES_CHECK(codes_set_long(h,"numberOfContributingSpectralBands",numberOfContributingSpectralBands),0);

    /* get as a long*/
    CODES_CHECK(codes_get_long(h,"numberOfContributingSpectralBands",&numberOfContributingSpectralBands),0);
    printf("numberOfContributingSpectralBands=%ld\n",numberOfContributingSpectralBands);

    /* get as a long*/
    CODES_CHECK(codes_get_size(h,"scaledValueOfCentralWaveNumber",&count),0);
    printf("count=%ld\n",(long)count);

    assert(count < sizeof(values)/sizeof(values[0]));

    size = count;
    CODES_CHECK(codes_get_long_array(h,"scaledValueOfCentralWaveNumber",values,&size),0);
    assert(size == count);

    for(i=0;i<count;i++) {
        printf("scaledValueOfCentralWaveNumber %lu = %ld\n",(unsigned long)i,values[i]);
        if (i == 0) assert( values[i] == 26870 );
        if (i == 1) assert( values[i] == 9272  );
    }

    for(i=0;i<count;i++)
        values[i] = i+1000;

    size = count;
    /* size--; */
    CODES_CHECK(codes_set_long_array(h,"scaledValueOfCentralWaveNumber",values,size),0);
    assert(size == count);

    /* check what we set */
    CODES_CHECK(codes_get_long_array(h,"scaledValueOfCentralWaveNumber",new_values,&size),0);
    assert(size == count);
    for(i=0;i<count;i++) {
        printf("Now scaledValueOfCentralWaveNumber %lu = %ld\n",(unsigned long)i,new_values[i]);
        assert( new_values[i] == (i+1000) );
    }

    codes_handle_delete(h);

    fclose(in);
    return 0;
}