There’s no new/delete equivalent of realloc in C++. From Bjarne Stroustrup’s FAQ : Why doesn’t C++ have an equivalent to realloc()? If you want to, you can of course use realloc(). However, realloc() is only guaranteed to work on arrays allocated by malloc() (and similar functions) containing objects without user-defined copy constructors. Also, please remember … Read more
If you are using shared_ptr or unique_ptr, you can specify a custom deleter. For example, struct free_delete { void operator()(void* x) { free(x); } }; This can be used with shared_ptr like so: std::shared_ptr<int> sp((int*)malloc(sizeof(int)), free_delete()); If you are using unique_ptr, the deleter is a part of the unique_ptr‘s type, so the deleter needs to … Read more
Once free()-d, I am expecting program’s virtual memory (VIRT) consumption to be down by 1MB. Well, this is not guaranteed by the C standard. It only says, once you free() the memory, you should not be accessing that any more. Whether the memory block is actually returned to the available memory pool or kept aside … Read more
It does not look like malloc is doing any checks at all. The fault that you get comes from hardware detecting a write to an invalid address, which is probably coming from malloc itself. When malloc allocates memory, it takes a chunk from its internal pool, and returns it to you. However, it needs to … Read more
Yes, you should still check for failures returned by malloc. In an environment that overcommits memory you will not be able to detect and recover from failures due to the environment running out of physical storage required when you write to parts of the address space that have been allocated to your program by a … Read more
From Open Groups’ specifications: If ptr is a null pointer, realloc() shall be equivalent to malloc() for the specified size. If ptr does not match a pointer returned earlier by calloc(), malloc(), or realloc() or if the space has previously been deallocated by a call to free() or realloc(), the behavior is undefined.
You can’t assign memory to an array. An array has a fixed size, for the whole of its lifespan. An array can never be null. An array is not a pointer. malloc returns the address to a memory block that is reserved for the program. You can’t “assign” that (being the memory block) to an … Read more
You need to cast away the const to initialize the fields of a malloc’ed structure: struct deneme *mydeneme = malloc(sizeof(struct deneme)); *(int *)&mydeneme->a = 15; *(int *)&mydeneme->b = 20; Alternately, you can create an initialized version of the struct and memcpy it: struct deneme deneme_init = { 15, 20 }; struct deneme *mydeneme = malloc(sizeof(struct … Read more
From http://wiki.answers.com/Q/Is_it_better_to_use_malloc_or_calloc_to_allocate_memory malloc() is faster, since calloc() initializes the allocated memory to contain all zeros. Since you typically would want to use and initialize the memory yourself, this additional benefit of calloc() may not be necessary.
The usual way is with (pseudo-code first): node = head # start at the head. while node != null: # traverse entire list. temp = node # save node pointer. node = node.next # advance to next. free temp # free the saved one. head = null # finally, mark as empty list. The basic … Read more