# usecases/c/UsesCase_MEDfield_2.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 2 : read the field of use case 1
     */

    #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 *verticesvalues = NULL;
      med_float *tria3values = NULL;
      med_float *quad4values = NULL;
      med_int nstep, nvalues;
      const med_int ncomponent = 1;
      int ret=-1;

      /* file creation */
      fid = MEDfileOpen("UsesCase_MEDfield_1.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;
      }

      /*
       * ... we know that the field values are defined on vertices and MED_TRIA3
       * and MED_QUAD4 cells, a real code working would check ...
       */

      /* MED_NODE */
      if ((nvalues = MEDfieldnValue(fid, fieldname, MED_NO_DT, MED_NO_IT, MED_NODE, MED_NONE)) < 0) {
        MESSAGE("ERROR : read number of values ...");
        goto ERROR;
      }

      if ((verticesvalues = (med_float *) malloc(sizeof(med_float)*nvalues*ncomponent)) == NULL) {
        MESSAGE("ERROR : memory allocation ...");
        goto ERROR;
      }
      if (MEDfieldValueRd(fid, fieldname, MED_NO_DT, MED_NO_IT, MED_NODE, MED_NONE,
                          MED_FULL_INTERLACE, MED_ALL_CONSTITUENT, (unsigned char*) verticesvalues) < 0) {
        MESSAGE("ERROR : read fields values on vertices ...");
        free(verticesvalues);
        goto ERROR;
      }
      free(verticesvalues);

      /* MED_TRIA3 */
      if ((nvalues = MEDfieldnValue(fid, fieldname, MED_NO_DT, MED_NO_IT, MED_CELL,
                                    MED_TRIA3)) < 0) {
        MESSAGE("ERROR : read number of values ...");
        goto ERROR;
      }
      if ((tria3values = (med_float *) malloc(sizeof(med_float)*nvalues*ncomponent)) == NULL) {
        MESSAGE("ERROR : memory allocation ...");
        goto ERROR;
      }
      if (MEDfieldValueRd(fid, fieldname, MED_NO_DT, MED_NO_IT, MED_CELL, MED_TRIA3,
                          MED_FULL_INTERLACE, MED_ALL_CONSTITUENT, (unsigned char*) tria3values) < 0) {
        MESSAGE("ERROR : read fields values for MED_TRIA3 cells ...");
        free(tria3values);
        goto ERROR;
      }
      free(tria3values);

      /* MED_QUAD4 */
      if ((nvalues = MEDfieldnValue(fid, fieldname, MED_NO_DT, MED_NO_IT, MED_CELL,
                                    MED_QUAD4)) < 0) {
        MESSAGE("ERROR : read number of values ...");
        goto ERROR;
      }
      if ((quad4values = (med_float *) malloc(sizeof(med_float)*nvalues*ncomponent)) == NULL) {
        MESSAGE("ERROR : memory allocation ...");
        goto ERROR;
      }
      if (MEDfieldValueRd(fid, fieldname, MED_NO_DT, MED_NO_IT, MED_CELL, MED_QUAD4,
                          MED_FULL_INTERLACE, MED_ALL_CONSTITUENT, (unsigned char*) quad4values) < 0) {
        MESSAGE("ERROR : read fields values for MED_QUAD4 cells ...");
        free(quad4values);
        goto ERROR;
      }
      free(quad4values);

      ret=0;
     ERROR:

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

      return ret;
    }