| Re: Passing string array to a DLM [message #33026] |
Fri, 29 November 2002 10:30 |
Randall Skelton
Messages: 169
Registered: October 2000
|
Senior Member |
|
|
Once again, as soon as the question is posted the answer magically
seems obvious.
The following works just fine:
for (i=0; i<n; i++) printf("Strings[%i]: %s\n", i,
(char *) strings[i].s);
On Fri, 29 Nov 2002, Randall Skelton wrote:
> Date: Fri, 29 Nov 2002 18:25:23 +0000
> From: Randall Skelton <rhskelto@atm.ox.ac.uk>
> Newsgroups: comp.lang.idl-pvwave
> Subject: Passing string array to a DLM
>
> Hi all,
>
> I've managed to stymie myself with a DLM yet again. In this case, I want
> to pass a single dimension string array from IDL into C and return a
> corresponding array of indicies. Accordingly from C, I want to be able to
> index through this string array calling a C function that processes the
> strings in a for-loop. Below is a sample that should segfault for IDL
> 5.x. My problem is basically that I cannot consistently index through the
> strings that are sitting in the argv[0]->value.arr->data pointer. I
> assume that this pointer points to the first IDL string structure so it
> is cast as (IDL_STRING *). I have tried various ways of sub-scripting and
> augmenting the 'strings->s' pointer and can get the next string in a
> hit-and-miss way that leaves me to believe I am truly missing something.
>
> Call in IDL as:
> a = test_passstrings(['blah', 'blah', 'blacksheep'])
>
> Any ideas?
>
> Thanks and happy thanksgiving :)
>
> Randall
>
>
> --- START: test.dlm ---
> MODULE TEST
> DESCRIPTION Testing passing a string array
> VERSION 1.0
> SOURCE Me
> BUILD_DATE November 2002
> FUNCTION TEST_PASSSTRINGS 1 1
> --- END: test.dlm ---
>
>
> --- START: test.c ---
>
> /* ANSI */
> #include <stdio.h>
> #include <stdlib.h>
> #include <math.h>
> #include <string.h>
>
> /* IDL */
> #include "export.h"
>
> /* Message Numbers */
> #define TEST_ERROR 0
>
> /* Useful macro */
> #define ARRLEN(arr) (sizeof(arr)/sizeof(arr[0]))
>
> extern IDL_MSG_BLOCK msg_block;
> extern void TEST_exit_handler(void);
> extern int TEST_Startup(void);
> extern IDL_VPTR IDL_CDECL
> TEST_PassStrings(int argc, IDL_VPTR argv[], char *argk);
>
> /* Globals here */
> static char statusBuffer[256]; /* for IDL message passing */
>
> static IDL_MSG_DEF msg_arr[] = {
> { "TEST_Error", "%NError: %s." },
> { "TEST_NOSTRINGARRAY", "%Nstring arrays not allowed %s"},
> };
>
> IDL_MSG_BLOCK msg_block;
>
> int IDL_Load(void) {
> /* Define the message block */
> if (!(msg_block = IDL_MessageDefineBlock("TEST", ARRLEN(msg_arr),
> msg_arr))) {
> return IDL_FALSE;
> }
>
> /* Call the startup function to add the routines to IDL. */
>
> /* Routines */
> if (!TEST_Startup()) {
> IDL_MessageFromBlock(msg_block, TEST_ERROR,
> IDL_MSG_RET, "Unable to initialize TEST interface");
> }
> return IDL_TRUE;
> }
>
> #ifdef __IDLPRE53__
> /* FOR IDL < 5.3 */
> /* Define the functions */
> static IDL_SYSFUN_DEF TEST_functions[] = {
> {TEST_PassStrings, "TEST_PASSSTRINGS", 1, 1, 0},
> };
> #else
> /* FOR IDL >= 5.3 */
> /* Define the functions */
> static IDL_SYSFUN_DEF2 TEST_functions[] = {
> {TEST_PassStrings, "TEST_PASSSTRINGS", 1, 1, 0, 0},
> };
> #endif
>
>
> /* Startup call when DLM is loaded */
> int TEST_Startup(void)
> {
>
> /* If IDL is pre-5.3 then change IDL_SysRtnAdd to IDL_AddSystemRoutine,
> * (NB: the parameters stay the same) */
>
> #ifdef __IDLPRE53__
> /* FOR IDL < 5.3 */
> /* Add functions */
> if (!IDL_AddSystemRoutine(TEST_functions, TRUE,
> ARRLEN(TEST_functions))) {
> return IDL_FALSE;
> }
> #else
> /* FOR IDL >= 5.3 */
> /* Add functions */
> if (!IDL_SysRtnAdd(TEST_functions, TRUE,
> ARRLEN(TEST_functions))) {
> return IDL_FALSE;
> }
> #endif
>
> /* Register the error handler */
> IDL_ExitRegister(TEST_exit_handler);
> return(IDL_TRUE);
> }
>
> /* Called when IDL is shutdown */
> void TEST_exit_handler(void) {
> /* Nothing special to do in this case */
> }
>
>
> /*---------------------------------------------------------- ------------------*/
> /* Function: TEST_PassStrings
> *
> * Purpose: Returns an index associated with the given name.
> *
> * Called in IDL as:
> * index = TEST_PassString('string')
> *
> * Where:
> * string = the field name (IDL_STRING)
> * index = returned index number
> *
> */
> IDL_VPTR IDL_CDECL TEST_PassStrings(int argc, IDL_VPTR argv[], char *argk) {
>
> /* Local */
> int i;
> IDL_STRING *strings;
> IDL_VPTR tmp;
> IDL_LONG *lonarr;
> IDL_LONG lDim[IDL_MAX_ARRAY_DIM];
> long n = 0;
>
> /* Get the field index from IDL */
> IDL_ENSURE_SIMPLE(argv[0]);
>
> /* Determine if passed argv is an array */
> if (argv[0]->flags & IDL_V_ARR) {
> /* ARGV IS AN ARRAY */
>
> /* Ensure we only pass one dimension */
> if (argv[0]->value.arr->n_dim > 1) {
> sprintf(statusBuffer,"Index cannot exceed one dimension");
> IDL_Message(IDL_M_NAMED_GENERIC, IDL_MSG_LONGJMP, statusBuffer);
> }
>
> /* Get the number of elements */
> n = argv[0]->value.arr->n_elts;
>
> /* Create the output string array */
> lDim[0] = n;
>
> lonarr = (IDL_LONG *) IDL_MakeTempArray((int) IDL_TYP_LONG, 1, lDim,
> IDL_ARR_INI_NOP, &tmp);
>
> strings = (IDL_STRING *) argv[0]->value.arr->data;
>
> /* ----- PROBLEM IS BELOW ----- */
> for (i=0; i<n; i++) printf("Strings[%i]: %s\n", i,
> (char *) strings->s + i * sizeof(IDL_STRING));
>
> /* for (i=0; i<n; i++) printf("Strings[%i]: %s\n", i,
> (char *) strings->s[i]); */
> /* ----- PROBLEM IS ABOVE ----- */
>
> /* Fill the array */
> for (i=0; i<n; i++) lonarr[i] = i;
>
> } else {
>
> /* Allocate a scalar long to return */
> tmp = IDL_GettmpLong(1);
>
> }
>
> return (tmp);
> }
>
> --- END: test.c ---
>
>
>
>
>
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