# usecases/c/UsesCase_MEDmesh_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/>.
     */

    /*
     *  Use case 2 : read a 2D unstructured mesh with 15 nodes, 8 triangular cells, 4 triangular cells
     */

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

    #include <string.h>

    int main (int argc, char **argv) {
      med_idt fid;
      const char meshname[MED_NAME_SIZE+1] = "2D unstructured mesh";
      char meshdescription[MED_COMMENT_SIZE+1];
      med_int meshdim;
      med_int spacedim;
      med_sorting_type sortingtype;
      med_int nstep;
      med_mesh_type meshtype;
      med_axis_type axistype;
      char axisname[2*MED_SNAME_SIZE+1];
      char unitname[2*MED_SNAME_SIZE+1];
      char dtunit[MED_SNAME_SIZE+1];
      med_float *coordinates = NULL;
      med_int nnodes = 0;
      med_int *triaconnectivity = NULL;
      med_int ntria3 = 0;
      med_int *quadconnectivity = NULL;
      med_int nquad4 = 0;
      med_bool coordinatechangement;
      med_bool geotransformation;
      int i;
      int ret = -1;

      /* open MED file with READ ONLY access mode */
      fid = MEDfileOpen("UsesCase_MEDmesh_1.med",MED_ACC_RDONLY);
      if (fid < 0) {
        MESSAGE("ERROR : open file in READ ONLY ACCESS mode ...");
        goto ERROR;
      }

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

      /* read mesh informations : mesh dimension, space dimension ... */
      if (MEDmeshInfoByName(fid, meshname, &spacedim, &meshdim, &meshtype, meshdescription,
                            dtunit, &sortingtype, &nstep, &axistype, axisname, unitname) < 0) {
        MESSAGE("ERROR : mesh info ...");
        goto ERROR;
      }

      /* read how many nodes in the mesh */
      if ((nnodes = MEDmeshnEntity(fid, meshname, MED_NO_DT, MED_NO_IT, MED_NODE, MED_NO_GEOTYPE,
                                   MED_COORDINATE, MED_NO_CMODE,&coordinatechangement,
                                   &geotransformation)) < 0) {
        MESSAGE("ERROR : number of nodes ...");
        goto ERROR;
      }

      /*
       * ... we know that we only have MED_TRIA3 and MED_QUAD4 in the mesh,
       * a real code working would check all MED geometry cell types ...
       */

      /* read how many triangular cells in the mesh */
      if ((ntria3 = MEDmeshnEntity(fid, meshname, MED_NO_DT, MED_NO_IT, MED_CELL,MED_TRIA3,
                                   MED_CONNECTIVITY, MED_NODAL,&coordinatechangement,
                                   &geotransformation)) < 0) {
        MESSAGE("ERROR : number of MED_TRIA3 ...");
        goto ERROR;
      }

      /* read how many quadrangular cells in the mesh */
      if ((nquad4 = MEDmeshnEntity(fid, meshname, MED_NO_DT, MED_NO_IT, MED_CELL,MED_QUAD4,
                                   MED_CONNECTIVITY, MED_NODAL, &coordinatechangement,
                                   &geotransformation)) < 0) {
        MESSAGE("ERROR : number of MED_QUAD4 ...");
        goto ERROR;
      }

      /* read mesh nodes coordinates */
      if ((coordinates = (med_float*) malloc(sizeof(med_float)*nnodes*spacedim)) == NULL) {
        MESSAGE("ERROR : memory allocation ...");
        goto ERROR;
      }

      if (MEDmeshNodeCoordinateRd(fid, meshname, MED_NO_DT, MED_NO_IT, MED_FULL_INTERLACE,
                                  coordinates) < 0) {
        MESSAGE("ERROR : nodes coordinates ...");
        goto ERROR;
      }

      /* read cells connectivity in the mesh */
      if ((triaconnectivity = (med_int *) malloc(sizeof(med_int)*ntria3*3)) == NULL) {
        MESSAGE("ERROR : memory allocation ...");
        goto ERROR;
      }
      if (MEDmeshElementConnectivityRd(fid, meshname, MED_NO_DT, MED_NO_IT, MED_CELL,
                                       MED_TRIA3, MED_NODAL, MED_FULL_INTERLACE, triaconnectivity) < 0) {
        MESSAGE("ERROR : MED_TRIA3 connectivity ...");
        goto ERROR;
      }

      if ((quadconnectivity = (med_int *) malloc(sizeof(med_int)*nquad4*4)) == NULL) {
        MESSAGE("ERROR : memory allocation ...");
        goto ERROR;
      }
      if (MEDmeshElementConnectivityRd(fid, meshname, MED_NO_DT, MED_NO_IT, MED_CELL,
                                       MED_QUAD4, MED_NODAL, MED_FULL_INTERLACE, quadconnectivity) < 0) {
        MESSAGE("ERROR : MED_TRIA3 connectivity ...");
        goto ERROR;
      }

      /*
       * ... we know that the family number of nodes and elements is 0, a real working would check ...
       */
      ret = 0;
     ERROR :

      /* memory desallocation */
      if (coordinates)
        free(coordinates);

      if (triaconnectivity)
        free(triaconnectivity);

      if (quadconnectivity)
        free(quadconnectivity);

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

      return ret;
    }