Thread: Hello question about the infamous pointers

Hello I am kind of stuck on this idea of how memory works in C.
Is the tmpPtr pointing to the 3rd element in the array or the 7th in the second if statement. If the later is that why I would use free()??? Thank you for any help given it is greatly appreciated.

Code:

int array[10], *ptrToArr;
ptrToArr = &array[0];

if(some condition){
    int *tmpPtr;
    tmpPtr = ptrToArr;
    printf("%d", *tmpPtr+4);
}

if(this is also true){
    int *tmpPtr;
    tmpPtr = ptrToArr;
    printf("%d", *tmpPtr+2)
}

ptrToArr++;

A better question would be why people think things like this help anyone understand pointers. Your questions:

s the tmpPtr pointing to the 3rd element in the array or the 7th in the second if statement.

Think of it in terms of distance from the starting element.

However in the section you are referencing, the code may be incorrectly written, since it dereferences tmpPtr first, then offsets that value by +2. It's no different from x + 2, if x were for example an integer. With pointers involved, you need to group the addition so it's performed first if what you mean is to dereference element 2. tmpPtr[2] is almost always clearer.

If the later is that why I would use free()???

You only need to free the pointers that malloc(), calloc() or realloc() returns.

The reason why you free() is because eventually the pointer to memory will fall out of scope, and be destroyed. Unless you call free() the memory you pointed to has no active references, and it just sits there being wasted, waiting to be released.