Question

I am working in C++ and have been using pointers a lot lately. I found that there are a few ways to initialize the chunks of memory that I need to use.

void functioncall(int* i)
{
    *i = *i + 1;
}

int main(){
    int* a = (int*)malloc(sizeof(int));
    int az = 0;

    functioncall(a);
    functioncall(&az);
}

Notice that the first variable int* a is declared as a pointer and then I malloc the memory for it. But, with az it is not a pointer but when calling the function I get the address of the memory.

So, my question is: is there a preferred way =, or is there any penalties one over the other?

Answer 1

int* a = (int*)malloc(sizeof(int));

This allocates memory on the heap. You have to deallocate it on your own, or you’ll run into memory leaks. You deallocate it by calling free(a);. This option is most definitely slower (since the memory has to be requested and some other background stuff has to be done) but the memory may be available as long as you call free.

---

int az = 0;

This “allocates” memory on the stack, which means it gets automatically destroyed when you leave the function it is declared (unless for some really rare exceptions). You do not have to tidy up the memory. This option is faster, but you do not have control over when the object gets destroyed.