I have made a simulation of a stack using malloc to create an array of MAX elements and assign it to a pointer. I then made a second pointer pointing to the first one, to be able to navigate back and forth, executing pushes and pops.
int * stack= (int *) malloc(MAX * sizeof(*stack));
int * stack_ptr = stack;
In the end, I delete the pointer containing the array, using
free (stack);
After I delete the array (stack), stack_ptr is pointing to an address with no contents, right?
Can this cause a memory leak or any kind of problem, even if the program terminates exactly after?
After I delete the array (stack), stack_ptr is pointing to an address with no contents, right?
After free(stack);, attempting to perform *stack_pt is undefined behavior (UB). The contents pointed to stack_pt may be good, bad or ugly or simply cause code to crash. It is UB to attempt to find out.
Can this cause a memory leak or any kind of problem, even if the program terminates exactly after?
Having a unchanged copy of the former valid pointer in stack_pt in itself in not a leak nor UB. Just don't use stack_pt.
Often after freeing, it is good practice to NULL the pointer(s).
int * stack= (int *) malloc(MAX * sizeof(*stack));
int * stack_ptr = stack;
...
free (stack);
stack = NULL;
stack_ptr = NULL;
Aside: Recommend to allocate to the size of the referenced object, not the type and forego the unneeded cast.
// int * stack= (int *) malloc(MAX * sizeof(*stack));
int *stack = malloc(sizeof *stack * MAX);