Problem: DLL using fclose doesn't close file unless exit Labview completly

[chrisml]

Hello,

Do I have more than one option to do this correctly? I do not want to be forced to stop and start
my Labview application every time I want to close a file.

    Thank you,
    Christopher Lusardi

[CharlieRodway]

Hi Christopher,

Can you exand on your question a little?

Are you calling a DLL from LabView, via Call Function Node?

[chrisml]

LabView is calling the DLL from a Call Function Node.

The DLL is a copy of the below code. Is there anything wrong with this code?

Christopher Lusardi

/*****************************­******************************­******************************­***/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

char file [100];

#include "my_header.h"

int create_file ()
{
  char Location [100] = "my_files/";
  FILE *Fptr;
  char box [50];
  int numalo = 0;
  int numdalo = 0;
  int mypid;
  int element;

  if ( gethostname (box, 50) < 0 )
  {
    printf ("gethostname failed\n");

    return (-1);
  }

  mypid = (int)getpid ();

  sprintf (file,"%s%s_%d",Location,box,m­ypid);

  if ( (Fptr = fopen (file,"w+")) == NULL )
  {
    printf ("fopen () failed opening file = %s\n",file);

    return (-1);
  }
  else
  {
    fprinttf (Fptr,"%d\n",Number_of_items);
    fprinttf (Fptr,"^^^^^^^^^^^^^^^^^^^^^^^­^^^\n");

    for (element = 0; element < Number_of_items;element++)
    {
      if ( vegetable [element] == 1024 )
      {
        fprintf (Fptr,"%d %d %X %d %d %X %X %X\n",
          vegetable [element],
          fruit,
          filtered_water.tomato [element],
          filtered_water.green [element],
          filtered_water.bacteria [element],
          filtered_water.organic [element],
          filtered_water.raw [element],
          filtered_water.washed [element]);
      }
      else
      {
        fprintf (Fptr,"%d %d %X %d %d %d %X %X\n",
          vegetable [element],
          fruit,
          filtered_water.tomato [element],
          filtered_water.green [element],
          filtered_water.bacteria [element],
          filtered_water.organic [element],
          filtered_water.raw [element],
          filtered_water.washed [element]);
      }
    }  
  }

  fclose (Fptr);

  return (0);

}

[CharlieRodway]

Hi Chistopher,

Where is Number_Of_Items being initialised?

[chrisml]

>Where is Number_Of_Items being initialised?

Number_Of_Items is incremented/decremented based on type of request asked of a service program.

This service routine is a separate program. Many applications, running at the same speed, make the requests.

If a resource is asked for the variable is incremented. If the resource is given up it is decremented.

There are about ~20 * 2 (really copies of the 1st 20) plus the DDL's routines used to accomplish this task, 

and a large prototype routine that does the same thing. Each different routine is for a different type of request.

Christopher Lusardi

[chrisml]

>   fprinttf (Fptr,"%d\n",Number_of_items);
>   fprinttf (Fptr,"^^^^^^^^^^^^^^^^^^^^^^^­^^^\n");

The above code segment is a typo. It should be:

 fprintf (Fptr,"%d\n",Number_of_items);
 fprintf (Fptr,"^^^^^^^^^^^^^^^^^^^^^^^­^^^\n");

Christopher Lusardi

[CharlieRodway]

Where is Number_of_items defined?  is it a static?

[chrisml]

> Where is Number_of_items defined?  is it a static?

It is initially defined in a dot h file for the main routine as

int Number_of_items;

and is accessed by including in many files (via another dot h file)

extern int Number_of_items;

It is set to 0 in a file that all users should use at the start of their main routines.

Christopher Lusardi

[chrisml]

O'kay, I was told that a GUI button was causing the problem. I investigated and was able to duplicate the problem

outside of the LabView environment. This means that the problem is not a DLL problem, and it is not a LabView problem.

Consequently, the problem is easier to solve, and I can do it on my own. I do not even think it is a fclose () problem.

Thank you for your mis-placed time,

Christopher Lusardi

[chrisml]

Hello again,

   I would like to reactivate this problem.

  The problem is I have to exit LabView completely and rerun the application to create a file if I use fp = fopen (...,"w+") as in earlier

posted code. If I do not restart LabView but I delete the file then on subsequent calls to fopen the file will not be created.

  What can I do to prevent exiting LabView but re-create the file on all calls to fopen or something like it?

 Thank you,

 Christopher Lusardi