Pointer Basics

Declare a pointer to an integer:

// declares `pointer_to_something` as a pointer to an int
int *pointer_to_something;

Get the address of a variable:

int meaning_of_life = 42;
int *pointer_to_mol = &meaning_of_life;
// pointer_to_mol now holds the address of meaning_of_life

Oftentimes we have a pointer, but we want to get access to the data that it points to. Not the address itself, but the value stored at that address.

We can use an asterisk (*) to do it. The * operator dereferences a pointer.

int meaning_of_life = 42;
int *pointer_to_mol = &meaning_of_life;
int value_at_pointer = *pointer_to_mol;
// value_at_pointer = 42

It can be a touch confusing, but remember that the asterisk symbol is used for two different things:

1. Declaring a pointer type: int *pointer_to_thing;
2. Dereferencing a pointer value: int value = *pointer_to_thing; (retrieving the value) or *pointer_to_thing = 20; (modifying the value)

Fix the change_filetype function (both in the .c and .h files). It should copy the struct from the pointer, update the copy, and leave the original unchanged.

1. Accept a pointer to a codefile_t, instead of a struct value
2. Dereference the pointer into the new_f codefile_t struct
3. The filetype field should still be changed to the provided new_filetype value
4. Still return the updated new_f codefile_t struct