A mechanism to free multiple regions on the heap at once

Question

Just to achieve clarity in my project, i want to avoid using free(3) in this manner:

free(ptr1);
free(ptr2);
.
.
.
free(ptrn);

So i had added a macro in this fashion

#define stop_point NULL
#define free_space(...){ \
void *ptrs[] = {__VA_ARGS__,stop_point};              \
for(int i=0;ptrs[i]!=stop_point;i++) free(ptrs[i]);}

And using it as following:

free_space(ptr1,ptr2,...ptrn);

I think this mechanism works but there is one problem, e.g. in the above line, if ptr2 is NULL, then other pointers following ptr2 (i.e. ptr3,ptr4...) will not get free. What i need is a better stop_point. How can i achieve that ?

Thank you.

Answer 1

Use a different sentinel. Change the macro to:

#define free_space(...) { \
    void *ptrs[] = { __VA_ARGS__, ptrs }; \
    for (int i = 0; ptrs[i] != ptrs; i++) free(ptrs[i]); }

or use the length of the array created from the list:

#define free_space(...) { \
    void *ptrs[] = { __VA_ARGS__ }; \
    for (size_t i = 0; i < sizeof ptrs / sizeof *ptrs; i++) free(ptrs[i]); }