INTERNAL: Creating IDL structs in C (Callable IDL)

Topic:
Creating IDL structs in C (Callable IDL)Discussion:
This program creates an array of IDL structures in C, and then manipulates them in IDL.Solution:

#include 
#include "export.h"
 
 
static void free_callback(UCHAR *addr)
{
  printf("IDL released(%u)\r
", addr);
}
 
 
 
int main(int argc, char **argv)
{
  int i, j;
 
  IDL_LONG dim[IDL_MAX_ARRAY_DIM];
 
  /* Set up the params for telling IDL the structure format. */
  static IDL_LONG three = 3;
  static IDL_LONG tag2_dims[] = {1,3};    /* Array of 3 IDL type FLOATs */
  static IDL_STRUCT_TAG_DEF s_tags[] =
    {{"TAG1", 0, (void *) IDL_TYP_LONG},
     {"TAG2", tag2_dims, (void *) IDL_TYP_FLOAT},
     {0}};
 
  /* Make the equivalent C structure. */
  typedef struct data_struct
  {
    IDL_LONG tag1_data;
    float tag2_data[3];
  } DATA_STRUCT;
 
  static DATA_STRUCT c_data[] = {{1,{2.0,3.0,4.0}},{5,{6.0,7.0,8.0}},{9,{10.0,11.0,12.0}}};
  void *s;
  IDL_VPTR v;
 
  static DATA_STRUCT *data;
 
 
  if (IDL_Init(0, &argc, argv))
  {
 
    dim[0] = 10;
 
    s = IDL_MakeStruct(0, s_tags);
 
    IDL_ExecuteStr("PRINT,'Array of structures created.'");
 
    /* HERE IS HOW TO GET AN ARRAY OF INITIALIZED STRUCTURES INTO IDL. */
 
    if (v = IDL_ImportNamedArray("TMP", 1, &three, IDL_TYP_STRUCT, (UCHAR *) &c_data, 0, s))
    {
    
      IDL_ExecuteStr("PRINT,'Array of initialized structures now passed into IDL as variable: TMP'");
      IDL_ExecuteStr("PRINT,'Pointed to by C variable \"v\"'");
      IDL_ExecuteStr("HELP, TMP");
      IDL_ExecuteStr("PRINT, TMP.TAG1, TMP.TAG2");
 
      printf("Here in C, the tags are:
");
      data =  (DATA_STRUCT *) v->value.s.arr->data;
      for(j = 0; j < 3; j++)
        printf(" %8d    ", data[j].tag1_data);
      printf("
");
      for(i = 0; i < 3; i++)
      {
        for(j = 0; j < 3; j++)
          printf("%12.3f ", data[i].tag2_data[j]);
        printf("
");
      }
 
      
      IDL_ExecuteStr("PRINT,'Change variable: TMP inside of IDL'");
      IDL_ExecuteStr("TMP.TAG1 = LINDGEN(3)*4");
      IDL_ExecuteStr("TMP.TAG2 = FINDGEN(3,3)*3.0");
      IDL_ExecuteStr("PRINT, TMP.TAG1, TMP.TAG2");
 
      printf("Here in C, the changed tags are:
");
      for(j = 0; j < 3; j++)
        printf(" %8d    ", data[j].tag1_data);
      printf("
");
      for(i = 0; i < 3; i++)
      {
        for(j = 0; j < 3; j++)
          printf("%12.3f ", data[i].tag2_data[j]);
        printf("
");
      }
 
 
      IDL_Cleanup(FALSE);    /* Don't return */
 
    }
  }
 
  return 1;
}