Re: HEAP error when trying to use free() help needed

From:

"io_x" <a@b.c.invalid>

Newsgroups:

comp.lang.c++

Date:

Wed, 8 Jun 2011 11:11:30 +0200

Message-ID:

<4def3c6c$0$18243$4fafbaef@reader2.news.tin.it>

"none" <none9823@hotmail.com> ha scritto nel messaggio
news:75366d67-4c83-46cf-a75b-6a953578b6f8@v12g2000vby.googlegroups.com...

I'm trying to figure out why this testing code do not work and produce
an error in VC++ when returning from the foo method.

here's the code:

   class test {
   public:
       char* pPointer;

       test (void) {
          pPointer = (char *) malloc (sizeof(char));

       }

       ~test () {
           free (pPointer); // HEAP error! when returning from foo
       }

       test test::foo (void) {
           test myfoo;
           return myfoo;
       }
   };

   ...

   test atest;
   atest = atest.foo(); // HEAP error!

   The pPointer seems to be already freed by foo, why is this? How
can I make this code work?

this is my try,
what does it? assign 255 to what pointer in atest point
i don't know if it is right, we are here for know where is wrong

#include <iostream.h>
#include <stdint.h>

#define u32 uint32_t
#define u8 uint8_t

class test {
  public:
  u8* cPointer;

  test(){cPointer=(u8*) malloc(sizeof(u8));
         printf("%p|", cPointer);
        }
~test(){printf("~%p|", cPointer);
         free(cPointer);
        }
  test(u8 a)
        {cPointer=(u8*) malloc(sizeof(u8));
         printf("%p|", cPointer);
         *cPointer=a;
        }

  test& fooVoid(void)
     {static test myfoo(255);
      return myfoo;
     }

  test& operator=(const test& a)
  {*cPointer=*a.cPointer;
   return *this;
  }

};

int main(void)
{test atest;
u32 v;

atest = atest.fooVoid();
cout << "atest.cPointer==" << (void*)atest.cPointer << "\n";
v=*atest.cPointer;
cout << "atest.cPointer.value==" << v << "\n";

return 0;
}

00862FD4|00862FE4|atest.cPointer==862fd4
atest.cPointer.value==255
~00862FD4|~00862FE4|

Thanks in advance