what is memory leak

blackzone · 11-03-2004, 07:47 PM

memory leak is a bug in program which cost program to not free memory, and it keep allocating memory until no more and program crash?

can someone give a really short simple program which have memory leak?

and show how to test it have memory leak?

itsme86 · 11-03-2004, 07:55 PM

Code:

int main(void)
{
  void *ptr;

  for(;;)
    ptr = malloc(1);

  return 0;
}

There's no real way to test if there's a memory leak. You just have to look at the code or notice that your program just keeps taking more and more memory for no reason.

vharishankar · 11-04-2004, 04:33 AM

A memory leak is technically when a pointer that has been allocated to a block of memory in the heap (also called global memory by some) has not been freed or the pointer variable has gone out of context without freeing the memory. In that case there is no way of referring to the allocated memory or freeing it. This is called a memory leak. The memory allocated will be locked off (unusable by other programs).

karlan · 11-04-2004, 09:41 PM

all you need to know is:

1) if malloc/new(nothrow) returns NULL, memory allocation failed, pointer points nowhere.
2) for every successful new/malloc you should eventually call a delete/free

If you aren't going to do any class allocation programming in c++, use malloc and free, the will make your life easier. there is no free/free[] crap, like with c++ delete

aizkorri · 11-05-2004, 02:54 AM

however, there are tools that check memory leaks in programs, I use them in a windows environment (rational purify) but there should be some for the LINUX environment.

itsme86 · 11-05-2004, 06:26 AM

A great one for Linux is Valgrind.

karlan · 11-05-2004, 10:32 AM

safe libc