how to prevent stack-overflow?

**albert3721** · 12-10-2007

hi all,
I write some codes based in recursive method(or some similar methods),eg. in maze-searching... they work ,but sometimes cause stack-overflow.
i try to write a function to prevent this, but i don't know if it works...
1: use a varible size to count the number of recursion times
2: after each call, check size using following code

Code:

.....
if (size == 4*BUFSIZ)//prevent stack overflow after too many setps
  {
    printf("\nMaze too large,Stack overflowed!");
    exit(0);
  }
...

the problem is that i'm not clear how many steps can a system stack hold...
plz help with this, thanks

**Elysia** · 12-10-2007

The stack has varying size depending on the system it's on. Some OS also allows you to set a new stack default. There's no portable, easy way of telling.

**matsp** · 12-10-2007

Like Elysia says, the stack may be "any" size - kernel stack in Windows is 8K [or at least it was on XP], whilst application stacks in Windows are "large" [as in hundreds of kilobytes or more - e.g. my gcc-compiled simple c++ code has a max stack-size of 2MB].

In embedded systems, there may be really small stacks, a few hundred bytes may well be sufficient to do certain processing in a 16-bit system.

The linker usually has some way to preset the stack-size to a max size - but it's dependent on the environment (compiler/linker & OS) what you have to do and what you CAN do [e.g. on a system with 64KB of memory, it's kind of hard to set a 2MB stack!]

--
Mats

**Salem** · 12-10-2007

> I write some codes based in recursive method(or some similar methods),eg. in maze-searching
Implement the equivalent non-recursive method instead.

Recursion is just a disguised loop, so you can always implement an equivalent iterative form.
If you do need to allocate space to preserve say your back-tracking information, you can always allocate some memory. The advantage is that you can easily spot the "out of memory" and take appropriate action.

There is no equivalent mechanism for telling you're about to run out of stack, how much memory each stack frame takes up, or how much stack there is to begin with.

**iMalc** · 12-10-2007

One can usually go into a very significant amount of recursion before blowing the stack. The thing that will unnecessarily limit you are declaring too many variables within the recursive function, and not taking advantage of performing tail-recursion elimination refactoring.

Certainly don't declare any arrays in the recursive function if you can at all help it.

Post the code here if it isn't too big and we'll help refactor it to remove unnecessary variables, and make it at least partially iterative if possible.

**VirtualAce** · 12-10-2007

You would want to return not exit(0) from a recursive call. Return will unwind the stack on the current call.

If you never return you are guaranteed to overflow the stack.

**albert3721** · 12-10-2007

Originally Posted by iMalc

Post the code here if it isn't too big and we'll help refactor it to remove unnecessary variables, and make it at least partially iterative if possible.

my code is too long to fit here , i'll manage to do it myself, thanks.

thank you guys

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