Simple answer : free(testPerson) is enough . Remember you can use free() only when you have allocated memory using malloc, calloc or realloc. In your case you have only malloced memory for testPerson so freeing that is sufficient. If you have used char * firstname , *last surName then in that case to store name … Read more
Question: “is malloc reentrant”? Answer: no, it is not. Here is one definition of what makes a routine reentrant. None of the common versions of malloc allow you to re-enter it (e.g. from a signal handler). Note that a reentrant routine may not use locks, and almost all malloc versions in existence do use locks … Read more
How should I pass a pointer to a function and allocate memory for the passed pointer from inside the called function? Ask yourself this: if you had to write a function that had to return an int, how would you do it? You’d either return it directly: int foo(void) { return 42; } or return … Read more
When an object is “double-freed”, the most common cause is that you’re (unnecessarily) releasing an autoreleased object, and it is later autoreleased when the containing autorelease pool is emptied. I’ve found that the best way to track down the extra release is to use the NSZombieEnabled environment variable for the affected executable in Xcode. For … Read more
Short Answer: It doesn’t, it just happens to be zero in your case.(Also your test case doesn’t show that the data is zero. It only shows if one element is zero.) Long Answer: When you call malloc(), one of two things will happen: It recycles memory that was previous allocated and freed from the same … Read more
malloc is used for dynamic memory allocation. As said, it is dynamic allocation which means you allocate the memory at run time. For example, when you don’t know the amount of memory during compile time. One example should clear this. Say you know there will be maximum 20 students. So you can create an array … Read more
jemalloc first appeared for FreeBSD, the brainchild of one “Jason Evans”, hence the “je”. I would ridicule him for being egotistical had I not once written an operating system called paxos 🙂 See this PDF for full details. It’s a white paper describing in detail how the algorithms work. The main benefit is scalability in … Read more
One-argument free(void *) (introduced in Unix V7) has another major advantage over the earlier two-argument mfree(void *, size_t) which I haven’t seen mentioned here: one argument free dramatically simplifies every other API that works with heap memory. For example, if free needed the size of the memory block, then strdup would somehow have to return … Read more
Is it true? Yes. Technically speaking, no part of: int *p = (int*)malloc(sizeof(int)); actually creates an object of type int, so dereferencing p is UB since there is no actual int there. Do we really have to call default constructor that is trivial to start the life time of the object? Do you have to … Read more
99.9% likely that you have corrupted memory (over- or under-flowed a buffer, wrote to a pointer after it was freed, called free twice on the same pointer, etc.) Run your code under Valgrind to see where your program did something incorrect.