Question

Assume the following situation:

typedef struct {
    int ID1;
    int ID2;
    char string[256];
} Reg;

I create an array dynamically, this structure:

Reg *myReg = (Reg*) malloc(sizeof(Reg)*100); //array of type Reg with 100 positions.

And throughout this example system, I fill this array.

There comes a certain point I do not want the pointer “myReg” point to this vector. I want him to point to NULL. And also to clear the memory space occupied by malloc I did.

question:

If I do:

free(myReg);

This will make myReg will point to NULL and release the space taken up that I’ve allocated?

Answer 1

free(myReg);

This will make myReg will point to NULL and release the space taken up
that I’ve allocated?

It will only release the memory. Even without reading the specs, if you look at how the free function is declared, you’ll see it can’t actually change what the pointer is pointing to.

/* Even if it wanted, `free` can't make `ptr` point to anything else. */
void free(void *ptr);