Question

Consider the following structure definitions and variable declarations: struct Customer { char lastName[ 15 ]; char firstName[ 15 ]; int customerNumber; struct { char phoneNumber[ 11 ]; char address[ 50 ]; char city[ 15 ]; char state[ 3 ]; char zipCode[ 6 ]; } personal; } customerRecord, *customerPtr; customerPtr = &customerRecord Write a separate expression that accesses the structure members in each of the following parts: a. Member lastName of structure customerRecord. b. Member lastName of the structure pointed to by customerPtr. c. Member firstName of structure customerRecord. d. Member firstname of the structure pointed to by customerPtr. e. Member customerNumber of structure customerRecord. f. Member customerNumber of the structure pointed to by customerPtr. g. Member phoneNumber of member personal of structure customerRecord. h. Member phoneNumber of member personal of the structure pointed to by customerPtr. i. Member address of member personal of structure customerRecord. j. Member address of member personal of the structure pointed to by customerPtr. k. Member city of member personal of structure customerRecord. I. Member city of member personal of the structure pointed to by customerPtr. m. Member state of member personal of structure customerRecord. n. Member state of member personal of the structure pointed to by customerPtr. 0\. Member zipcode of member personal of structure customerRecord. p. Member zipcode of member personal of the structure pointed to by customerPtr.

Short answer

Expressions use the dot operator (.) for `customerRecord` and arrow operator (->) for `customerPtr` to access members.

Step-by-step solution

Accessing lastName Directly

Use the dot operator to access the member `lastName` directly from the structure `customerRecord`. The expression is `customerRecord.lastName`.

Accessing lastName via Pointer

Use the arrow operator to access the member `lastName` through the pointer `customerPtr`. The expression is `customerPtr->lastName`.

Accessing firstName Directly

Use the dot operator to access the member `firstName` directly from the structure `customerRecord`. The expression is `customerRecord.firstName`.

Accessing firstName via Pointer

Use the arrow operator to access the member `firstName` through the pointer `customerPtr`. The expression is `customerPtr->firstName`.

Accessing customerNumber Directly

Use the dot operator to access the member `customerNumber` directly from the structure `customerRecord`. The expression is `customerRecord.customerNumber`.

Accessing customerNumber via Pointer

Use the arrow operator to access the member `customerNumber` through the pointer `customerPtr`. The expression is `customerPtr->customerNumber`.

Accessing phoneNumber of personal Directly

First, use the dot operator to access the nested structure `personal`. Then, use another dot operator to access `phoneNumber`. The expression is `customerRecord.personal.phoneNumber`.

Accessing phoneNumber of personal via Pointer

First, use the arrow operator to access the nested structure `personal` within `customerPtr`, and then use the dot operator to access `phoneNumber`. The expression is `customerPtr->personal.phoneNumber`.

Accessing address of personal Directly

First, use the dot operator to access the nested structure `personal`. Then, use another dot operator to access `address`. The expression is `customerRecord.personal.address`.

Accessing address of personal via Pointer

First, use the arrow operator to access the nested structure `personal` within `customerPtr`, and then use the dot operator to access `address`. The expression is `customerPtr->personal.address`.

Accessing city of personal Directly

First, use the dot operator to access the nested structure `personal`. Then, use another dot operator to access `city`. The expression is `customerRecord.personal.city`.

Accessing city of personal via Pointer

First, use the arrow operator to access the nested structure `personal` within `customerPtr`, and then use the dot operator to access `city`. The expression is `customerPtr->personal.city`.

Accessing state of personal Directly

First, use the dot operator to access the nested structure `personal`. Then, use another dot operator to access `state`. The expression is `customerRecord.personal.state`.

Accessing state of personal via Pointer

First, use the arrow operator to access the nested structure `personal` within `customerPtr`, and then use the dot operator to access `state`. The expression is `customerPtr->personal.state`.

Accessing zipCode of personal Directly

First, use the dot operator to access the nested structure `personal`. Then, use another dot operator to access `zipCode`. The expression is `customerRecord.personal.zipCode`.

Accessing zipCode of personal via Pointer

First, use the arrow operator to access the nested structure `personal` within `customerPtr`, and then use the dot operator to access `zipCode`. The expression is `customerPtr->personal.zipCode`.

Key concepts

Understanding Pointer to Structure

When programming in C++, structures are a handy way to store related variables under one name. But what happens when you want to pass these structures to different functions or manipulate them without copying the entire structure? This is where pointers to structures come in.

• A pointer to a structure is just like a regular pointer. It stores the memory address of the structure, so you can easily access and modify the data it points to.
• By declaring a pointer to a structure, you can point to and work with the data of the original structure without having to create a duplicate copy.
• Accessing structure members through a pointer requires using the arrow operator (->), which we'll talk about more in a later section.

If you have a structure, say `Customer customerRecord`, you can create a pointer `Customer* customerPtr`. By assigning and pointing `customerPtr` to `customerRecord`'s address using `customerPtr = &customerRecord`, you can efficiently access all parts of the structure.

Exploring Nested Structures

Nested structures in C++ are essentially structures within structures. This allows for more organized and hierarchical data management, especially when dealing with complex data.

• Imagine you have a `Customer` structure that also needs to store detailed `personal` information. Instead of combining all these data directly, you can create a nested structure for `personal`.
• Nesting is beneficial for maintaining a clean and readable code by logically grouping related data together.
• In our example, the `personal` info contains fields like `phoneNumber` and `address`. When a structure like this is nested, accessing its members involves a little extra navigation.

To access a member of a nested structure directly, you would use the dot operator multiple times, like `customerRecord.personal.phoneNumber`. We'll dive into the dot operator next.

Using the Dot Operator

The dot operator is a basic yet powerful tool in C++ for accessing members of a structure. It's straightforward and best used when dealing with structures directly rather than through pointers.

• When you work with an instance of a structure, the dot operator helps to pull out or manipulate specific members contained within that structure.
• For example, if you have `customerRecord`, and you want to access `lastName` directly, you use `customerRecord.lastName`.
• With nested structures, the dot operator can be chained to access deeper levels, like `customerRecord.personal.city`.

It's important to note that the dot operator is only applicable when you are working with structure variables directly, not through pointers.

Mastering the Arrow Operator

The arrow operator (->) in C++ is key when you work with pointers to structures. It simplifies accessing the members of a structure through a pointer.

• The arrow operator is shorthand for dereferencing a pointer to access a structure member. It combines `*` (dereference) and `.` (dot) operations, saving you extra characters and making the code cleaner.
• When using the arrow operator, you can easily access any member of a structure pointed to by a pointer, such as `customerPtr->lastName`.
• It's particularly handy when dealing with complex structures and pointers, allowing you to access even nested structure members seamlessly.

For instance, if `customerPtr` points to `customerRecord`, and you need the `city` in the nested `personal` structure, you can write it as `customerPtr->personal.city`. This approach keeps your code neat and efficient, especially with intricate data structures.