Heap Problems: Typo in previous mail

[Sudipto Banerjee]

Hi,

There was a typo in my previous mail: I was using "delete [] v" instead of
delete v as was typed there. I give below my full earlier mail with the correction.

Thanks and hoping to hear from someone.

Hi all,

I actually write numerical simulations as console applications for my research
in C++. I have encountered the following problem with VC++ 6.0 which some
have called a bug in the Microsoft compiler. I present here just a small
test program that will, I hope, elucidate the point.

Before you look at the program: This worked fine with g++ (on Linux) and
with Borland C++ on Windows 2000. But in VC++6.0 on Windows 2000, for l=8,
j = 31, i = 10169 and k = 105 in the nested loop in "main" it threw an exception
break point complaining about sometinhg in _heap_alloc_dbg(,) and also looking
for a dbgheap.c file!!! Initially I thought it was some memory leakage but
I checked for them using the CRT functions and also assert. There was no
such stuff going on. In any case, it is a simple test function where I dynamically
allocate (using new) and almost immediately deallocate using delete! Also,
a more C-like version using malloc and free gives the exact same problem.


May anyone suggest some way of going around this problem in VC++ 6.0? Any
help/suggestions will be greatly appreciated.

Thanks for the attn. The code snippet follows below.

#include <iostream>
#include <cassert>

double test (int i, int j);

using namespace std;

int main ()
{
double u = 0.0;
int i, j, k, l;

for (l = 0; l < 26; l++) {
for (j = 0; j < 99; j++) {
for (i = 0; i < 17325; i++) {
for (k = 0; k < 301; k++) u = test(i,k);
}
}
}
}

return 0;
}

double test (int i, int k)
{
int j;
double *v, temp;

v = new double [10];
assert (v);

for (j = 0; j < 10; j++) v[j] = 2*j+1;

temp = v[0]*v[5];

delete [] v;
v = 0;

return temp
}

[ralph]

"Sudipto Banerjee" <sudiptob@biostat.umn.edu> wrote:
>
>Hi,
>
>There was a typo in my previous mail: I was using "delete [] v" instead
of
>delete v as was typed there. I give below my full earlier mail with the
correction.
>
>Thanks and hoping to hear from someone.
>
>Hi all,
>
>I actually write numerical simulations as console applications for my research
>in C++. I have encountered the following problem with VC++ 6.0 which some
>have called a bug in the Microsoft compiler. I present here just a small
>test program that will, I hope, elucidate the point.
>
>Before you look at the program: This worked fine with g++ (on Linux) and
>with Borland C++ on Windows 2000. But in VC++6.0 on Windows 2000, for l=8,
>j = 31, i = 10169 and k = 105 in the nested loop in "main" it threw an exception
>break point complaining about sometinhg in _heap_alloc_dbg(,) and also looking
>for a dbgheap.c file!!! Initially I thought it was some memory leakage but
>I checked for them using the CRT functions and also assert. There was no
>such stuff going on. In any case, it is a simple test function where I dynamically
>allocate (using new) and almost immediately deallocate using delete! Also,
>a more C-like version using malloc and free gives the exact same problem.
>
>
>May anyone suggest some way of going around this problem in VC++ 6.0? Any
>help/suggestions will be greatly appreciated.
>
>Thanks for the attn. The code snippet follows below.
>
>#include <iostream>
>#include <cassert>
>
>double test (int i, int j);
>
>using namespace std;
>
>int main ()
>{
> double u = 0.0;
> int i, j, k, l;
>
> for (l = 0; l < 26; l++) {
> for (j = 0; j < 99; j++) {
> for (i = 0; i < 17325; i++) {
> for (k = 0; k < 301; k++) u = test(i,k);
> }
> }
> }
> }
>
> return 0;
>}
>
>double test (int i, int k)
>{
> int j;
> double *v, temp;
>
> v = new double [10];
> assert (v);
>
> for (j = 0; j < 10; j++) v[j] = 2*j+1;
>
> temp = v[0]*v[5];
>
> delete [] v;
> v = 0;
>
> return temp
>}
>

There are several more syntax errors: An extra Brace in Main() and a missing
semicolon in the 'return()' statement in test().

Once these were corrected the program ran to completion without error on
my system (Win2k, 512 ram).

_heap_alloc_dbg() is the malloc function called when using new for a debug
compile. It is responsible for not only allocating memory but also filling
the memory with bogus values. Your program does a "Ton" of allocations and
the fact _heap_alloc_dbg() was named as the source of the error means simply
that an allocation from the heap eventually failed. This would be consistent
with having used "delete v", instead of "delete [] v".