# usecases/c/UsesCase_MEDfield_5.c

    /*  This file is part of MED.
     *
     *  COPYRIGHT (C) 1999 - 2012  EDF R&D, CEA/DEN
     *  MED is free software: you can redistribute it and/or modify
     *  it under the terms of the GNU Lesser General Public License as published by
     *  the Free Software Foundation, either version 3 of the License, or
     *  (at your option) any later version.
     *
     *  MED is distributed in the hope that it will be useful,
     *  but WITHOUT ANY WARRANTY; without even the implied warranty of
     *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     *  GNU Lesser General Public License for more details.
     *
     *  You should have received a copy of the GNU Lesser General Public License
     *  along with MED.  If not, see <http://www.gnu.org/licenses/>.
     */

    /*
     * Field use case 5 : read a field with following with computing steps
     */

    #include <med.h>
    #define MESGERR 1
    #include <med_utils.h>

    #include <string.h>

    int main (int argc, char **argv) {
      med_idt fid;
      char meshname[MED_NAME_SIZE+1]="";
      med_bool localmesh;
      const char fieldname[MED_NAME_SIZE+1] = "TEMPERATURE_FIELD";
      med_field_type fieldtype;
      char componentname[MED_SNAME_SIZE+1]="";
      char componentunit[MED_SNAME_SIZE+1]="";
      char dtunit[MED_SNAME_SIZE+1]="";
      med_float *values = NULL;
      med_int nstep, nvalues;
      med_int ncomponent = 1;
      med_int csit, numit, numdt, meshnumit, meshnumdt, it;
      med_float dt;
      med_geometry_type geotype;
      med_geometry_type *geotypes = MED_GET_CELL_GEOMETRY_TYPE;
      int ret=-1;

      /* open file */
      fid = MEDfileOpen("UsesCase_MEDfield_4.med",MED_ACC_RDONLY);
      if (fid < 0) {
        MESSAGE("ERROR : open file ...");
        goto ERROR;
      }

      /*
       * ... we know that the MED file has only one field with one component ,
       * a real code working would check ...
       */

      /*
       * if you know the field name, direct access to field informations
       */
      if (MEDfieldInfoByName(fid, fieldname, meshname, &localmesh, &fieldtype,
                             componentname, componentunit, dtunit, &nstep) < 0) {
        MESSAGE("ERROR : Field info by name ...");
        goto ERROR;
      }

      /*
       * Read field values for each computing step
       */
      for (csit=0; csit<nstep; csit++) {

        if (MEDfieldComputingStepMeshInfo(fid, fieldname, csit+1, &numdt, &numit, &dt,
                                          &meshnumdt, &meshnumit) < 0) {
          MESSAGE("ERROR : Computing step info ...");
          goto ERROR;
        }

      /*
       * ... In our case, we suppose that the field values are only defined on cells ...
       */
        for (it=1; it<=MED_N_CELL_FIXED_GEO; it++) {

          geotype = geotypes[it];

          if ((nvalues = MEDfieldnValue(fid, fieldname, numdt, numit, MED_CELL, geotype)) < 0) {
            MESSAGE("ERROR : read number of values ...");
            goto ERROR;
          }

          if (nvalues) {
            if ((values = (med_float *) malloc(sizeof(med_float)*nvalues*ncomponent)) == NULL) {
              MESSAGE("ERROR : memory allocation ...");
              goto ERROR;
            }
            if (MEDfieldValueRd(fid, fieldname, numdt, numit, MED_CELL, geotype,
                                MED_FULL_INTERLACE, MED_ALL_CONSTITUENT, (unsigned char*) values) < 0) {
              MESSAGE("ERROR : read fields values for cells ...");
              free(values);
              goto ERROR;
            }
            free(values);
          }
        }
      }

      ret=0;
     ERROR:

      /* close file */
      if (MEDfileClose(fid) < 0) {
        MESSAGE("ERROR : close file ...");
        ret=-1;
      }

      return ret;
    }