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Similar to other derived types, like arrays and strings, structures can use a lot of memory. Imagine a structure with multiple strings each able to hold hundreds of characters.

One way to manage memory while working on data types of this size is to use pointers. As a reminder, a pointer is a variable that holds the memory address to another variable.

For structures, this is accomplished by first defining the structure variable, then defining a pointer and assigning it the address to the structure variable.

struct Bottle myBottle = {"Medium Bottle", 24, 0}; struct Bottle* bottlePointer = &myBottle;

In the above example, bottlePointer holds the memory address pointing to myBottle.

To access member variables with bottlePointer and the dot operator we can use the following syntax:

(*bottlePointer).name; (*bottlePointer).maxCapacity; (*bottlePointer).currentCapacity;

When using pointers we need to dereference, *, the address to access the variable it points to. When using the dot operator with structure pointers, we also need to wrap the dereference in parenthesis, (). If we simply dereference like *aPointer.name, it will result in an error.

Arrow notation can also be used with pointers to structures, as it implicitly does the dereferencing for you.

aPointer->name; aPointer->maxCapacity; aPointer->currentCapacity;

Notice how much better the arrow notation reads compared to dot notation. This notation is a clear and simple way to work with user-defined structure pointers.

Instructions

1.

The workspace has two Person data types named person1 and person2.

In the main() function:

  • Create a pointer to person1 called person1Pointer
  • Create another pointer that points to person2 called person2Pointer
2.

Now make some changes to person1.

After the pointer definition and using dereferencing and dot notation:

  • Add 1 to the member variable age of person1
3.

Now change the other structure data.

Using arrow notation:

  • Add 10 to the member variable age of person2

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