eccodes/examples/C/bufr_set_keys.c

/*
 * Copyright 2005-2015 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_set_keys
 *
 * Description: how to set different type of keys in BUFR messages.
 *
 */

#include "eccodes.h"

void usage(char* prog) {
    printf("usage: %s infile\n",prog);
    exit(1);
}

int main(int argc,char* argv[])
{
    FILE* in = NULL;
    FILE* out = NULL;
    
    /* message handle. Required in all the eccodes calls acting on a message.*/
    codes_handle* h=NULL;
    
    long longVal;
    /*double doubleVal;*/
    int i, err=0;
    int cnt=0;
    size_t size = 0;
    char* infile = "../../data/bufr/syno_multi.bufr";
    const void *buffer = NULL;
    
    if (argc != 2) {
        usage(argv[0]);
        return 1;
    }

    in = fopen(infile,"r");
    out = fopen(argv[1],"w");

    if (!in || !out) {
        perror("ERROR: unable to open files");
        fclose(out);
        fclose(in);
        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) {
            printf("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);*/
    
        /* This is the place where you may wish to modify the message*/
        /*E.g. we change the centre and 2m temperature */
           
        /* set centre */
        longVal=222;
        CODES_CHECK(codes_set_long(h, "centre", longVal),0);
        printf("  set centre to: %ld\n",longVal);
        
        /* check centre */
        CODES_CHECK(codes_get_long(h,"centre",&longVal),0);
        printf("  centre's new value is: %ld\n",longVal);
        
        /*doubleVal=240.+i*2.;
        CODES_CHECK(codes_set_double(h,"airTemperatureAt2M",doubleVal),0);
        printf("  set airTemperatureAt2M to: %f\n",doubleVal);*/
        
        /* get the modified message in a buffer */
        CODES_CHECK(codes_get_message(h,&buffer,&size),0);
       
        /* write the buffer to a file */
        if(fwrite(buffer,1,size,out) != size) {
            perror(argv[0]);
            return 1;
        }
 
        /* delete handle */
        codes_handle_delete(h);
        
        cnt++;
    }
    
    fclose(in);
    return 0;
}