Deleting a class from dll causes error

[butthead]

access violation at address xxxxxxxx in module test.dll
write of address xxxxxxxx

and I somtimes get a read address of FFFFFFFF error

I have a class that is instantiated with new from a dll.
when I delete it I get the error.

if I just create the class object as so in a function

Classwidget cw;

when it comes to the end of the function it destroys itself
and there is no problem.

what could be the cause of the error on the delete.

TC

 

[2ffat]

I hate access violations. They are a royal pain to track down. Is it possible that something is trying to call that class after it has been deleted? Maybe a scope problem?

James P. Cottingham
-----------------------------------------
^{I'm number 1,229!
I'm number 1,229!}

 

[butthead]

I am using this to time the operations of a
database engine I am building. such as load
a table, post, next, etc...

I just cant seem to use new and delete on it.
as the delete goes awry. I have solved some of
the usage problems by declaring

StopWatch sw;

as a global. This solves a lot of usage problems,
but the access violation seems to point to a problem
that should be fixed.

I have used new to create an instance of stopwatch
on a buttonclick and then immediately used delete.
Nothing else. then, bang all heck you know what.

it has been interesting though to watch the results.
if I instantiate the stopwatch object with just the
declaration as above and let the clas destroy itself
by falling through the function I discover that the
construction of this small object is very time consuming.

0.034 seconds as opposed to the quite small amount of
time (usually under a milisecond) to call small functions.

#include <ctime>
#include <stdio.h>
#include <string.h>

using namespace std;
const int strl = 100;

class __declspec(dllexport) StopWatch
{
    public:

        StopWatch (int Log = 0, char *str = "StopWatch :")
                    : FileName ("Stopwatch.log")
        {
            LogFile = Log;
            if (strlen (str) < strl)
                strcpy (string, str);

            start = clock();
        }

        ~StopWatch ();
        double Stop ();
        void Reset ();
        void LeadString (const char *str);
        
    private:

        clock_t start;
        int LogFile;
        char string [strl];
        const char *FileName;
};

#include "stopwatch.h"

using namespace std;


__declspec(dllexport) StopWatch::~StopWatch()
{
    clock_t total = clock () - start; //get elapsed time

    if (LogFile >= 2)
    {
        FILE *file;
        file = fopen (FileName, "a");
        fprintf (file, "%s: %s%.3f\n", string, "(destruct) total elapsed time in seconds: ", (total)/CLOCKS_PER_SEC);
        fclose (file);
    }
}

double __declspec(dllexport) StopWatch::Stop()
{
    clock_t total = clock () - start; //get elapsed time

    if ((LogFile == 1) || (LogFile == 3))
    {
        FILE *file;
        file = fopen (FileName, "a");
        fprintf (file, "%s: %s%.3f\n", string, "(stop) total elapsed time in seconds: ", (total)/CLOCKS_PER_SEC);
        fclose (file);
    }

    return total/CLOCKS_PER_SEC;
}

void __declspec(dllexport) StopWatch::Reset ()
{
    start = clock ();   
}

void __declspec(dllexport) StopWatch::LeadString (const char *str)
{
    strcpy (string, str);
}

as stated earlier this class is in a DLL

TC

 

[butthead]

I forgot

the first is the h file
the second is the cpp

though I am sure that is obvious

grins

TC