So, let's summarize the key points regarding the usage of the free API:
- The parameter passed to free(3) must be a value returned by one of the malloc(3) family APIs (malloc(3), calloc, or realloc[array]).
- free has no return value.
- Calling free(ptr) does not set ptr to NULL (that would be nice, though).
- Once freed, do not attempt to use the freed memory.
- Do not attempt to free the same memory chunk more than once (it's a bug – UB).
- For now, we will assume that freed memory goes back to the system.
- For Heaven's sake, do not forget to free memory that was dynamically allocated earlier. The forgotten memory is said to have leaked out and that's a really hard bug to catch! Luckily, there are tools that help us catch these ...
