| Importing nested structures? [message #15851] |
Tue, 15 June 1999 00:00 |
skerr
Messages: 2
Registered: June 1999
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Junior Member |
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Dear IDL gurus,
A colleague and I are very confused about the proper use of the
IDL_MakeStruct and IDL_ImportNamedArray routines. Specifically,
what do you do with the "type" field of an IDL_STRUCT_TAG_DEF
when structures are nested? The IDL 4 Advanced Development Guide
is a bit vague on this point. It says it is "either a pointer to
another structure type definition, or a simple IDL type cast to
void (e.g., (void *) IDL_TYP_BYTE)."
For a nested structure, this suggests it could either be another
IDL_STRUCT_TAG_DEF defined previously, or (void *) IDL_TYP_STRUCT.
The strange thing is, both work in IDL 4, at least for the sample
program I have appended below. My colleague discovered that NULL
also works in IDL 5.
Does anyone know what the correct syntax is that will work in both
IDL 4 and IDL 5?
Regards,
S. Kerr
-------------------- sample program appended ------------------------
#include <stdio.h>
#include "/usr/local/rsi/idl/external/export.h"
int main(int argc, char **argv)
{
static IDL_LONG one = 1;
static IDL_STRUCT_TAG_DEF substruct_tags[] = {
{"P", 0, (void *) IDL_TYP_INT},
{"Q", 0, (void *) IDL_TYP_INT},
{0}
};
static IDL_LONG matrix_dims[] = {2,2,2};
static IDL_LONG substruct_dims[] = {1,1};
static IDL_STRUCT_TAG_DEF s_tags[] = {
{ "MATRIX", matrix_dims, (void *) IDL_TYP_FLOAT},
{ "SUBSTRUCT", substruct_dims, substruct_tags},
/* should we use (void *) IDL_TYP_STRUCT instead of substruct_tags? */
{0}
};
typedef struct substruct {
short int p;
short int q;
} SUBSTRUCT;
typedef struct data_struct {
float mat [2] [2];
SUBSTRUCT sub;
} DATA_STRUCT;
static DATA_STRUCT s_data, *s_new_data;
void *s;
IDL_VPTR v;
int i,j;
IDL_Init(0,&argc,argv);
s_data.mat[0][0] = s_data.mat[1][1] = 1.0;
s_data.mat[0][1] = s_data.mat[1][0] = 0.0;
s_data.sub.p = -999;
s_data.sub.q = +1001;
s = IDL_MakeStruct("FOO", s_tags);
printf("Almost all folks.\n");
v = IDL_ImportNamedArray("FOO",1,&one,IDL_TYP_STRUCT,
(UCHAR *) &s_data, 0, s);
s_new_data = (DATA_STRUCT *) v->value.s.arr->data;
for (i=0;i<2;i++)
for (j=0;j<2;j++)
printf("%f\n",s_new_data->mat[i][j]);
printf("%i\n", s_new_data->sub.p);
printf("%i\n", s_new_data->sub.q);
printf("That's all folks.\n");
}
---------------------- end of sample program ------------------------------
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