| CALL_EXTERNAL PROBLEM [message #38290] |
Mon, 01 March 2004 20:24 |
scuaic
Messages: 3
Registered: February 2004
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Junior Member |
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Hello all.
I am trying to use call_external to call a .dll file which opens a
.txt file and read some information from it (don't ask why :) ). I am
writing my C code using Microsoft Visual C++ 6.0. My code looks like
this:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "idl_export.h"
/* TO EXTRACT INFORMATION FROM CONTROL FILE */
extern void error(const char *); /* prints errors */
BOOL APIENTRY DllMain( HANDLE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
)
{
return TRUE;
}
_declspec(dllexport) IDL_LONG IDL_CDECL program_control(IDL_INT *set,
IDL_INT *n)
{
/* CONTROL FILE RELATED VARIABLES */
FILE *fp1; /* FILE POINTERS */
char dest[100];
char ch;
int check = 1, i;
/* OPEN CONTROL FILE */
if ((fp1 = open("control.txt","r")) == NULL) {
error("can't open control file");
return 0;
}
/* IGNORE COMMENTS */
etc...
} /* END OF PROGRAM_CONTROL FILE */
Central to my goal is the problem of opening the 'control.txt' file
using fopen() or open(), which is not happening for some reason. The
fopen() function sometimes returns a NULL file pointer, and sometimes
a valid one. The times when it does return a valid pointer, the
variable 'fp1' just "NULLS" it somehow. I am debuging this by spawning
the IDLDE process.
I did see some posting in this regard before but didn't see any clear
solution to the problem. Perhaps it has never been discussed on this
newsgroup? Does anyone have a clue why this is happening?? Is there
something i am missing in order to open and r/w files from within a
.dll??
Along the same lines, I was also wondering how one might get the
informational messages i.e.
fprintf(stderr, "bla bla..\n");
to show up in IDL??
Any help will be greatly appreciated. Thanks.
--
Saurabh Srivastava
Graduate Research Assistant
Department of Electrical & Computer Engineering
University of Arizona
Tucson, AZ.
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