Question

Write \(\mathrm{C}++\) statements that do the following: a. Define an enum type, courseType, with the values ALGEBRA, BEGINNING SPANISH, ASTRONOMY, GBNBRAL CHBMISTRY, PHYSICS, and LOGIC. b. Declare a variable newClass of the type courseType. c. Assign ASTRONOMY to the variable newClass. d. Advance newClass to the next value in the list. e. Output the value of the variable newClass. f. Input value in the variable newClass.

Short answer

Define an enum, declare and assign values to it, increment and output the value, and handle user input with conversions.

Step-by-step solution

Define the Enum Type

To define an enum type called `courseType` with the given values, you can use the `enum` keyword in C++. The syntax is as follows: ```cpp enum courseType { ALGEBRA, BEGINNING_SPANISH, ASTRONOMY, GENERAL_CHEMISTRY, PHYSICS, LOGIC }; ```

Declare the Enum Variable

You need to declare a variable of the type `courseType`. This is done similarly to how you'd declare a variable of any other type: ```cpp courseType newClass; ```

Assign a Value to the Variable

To assign the value `ASTRONOMY` to the previously declared variable `newClass`, you simply use the assignment operator: ```cpp newClass = ASTRONOMY; ```

Advance to the Next Enum Value

To advance `newClass` to the next enumerated value in the list, you can increment it as if it were an integer: ```cpp newClass = static_cast(newClass + 1); ```

Output the Enum Variable

To output the current value of `newClass`, you can use the `cout` object from the `iostream` library. Typically, you would also implement a way to convert enum values to strings for readable output: ```cpp #include const char* courseNames[] = {"ALGEBRA", "BEGINNING_SPANISH", "ASTRONOMY", "GENERAL_CHEMISTRY", "PHYSICS", "LOGIC"}; std::cout << courseNames[newClass] << std::endl; ```

Input a Value into the Variable

To input a value into `newClass` from the user, you can use `cin` and convert it to the enum type. However, proper conversion from user input to enum type requires careful handling: ```cpp int input; std::cout << "Enter a number (0 for ALGEBRA, 1 for BEGINNING_SPANISH,..., 5 for LOGIC): "; std::cin >> input; if (input >= 0 && input <= 5) { newClass = static_cast(input); } else { std::cout << "Invalid input." << std::endl; } ```

Key concepts

enum type

In C++, an `enum` or enumeration is a user-defined type that allows you to assign symbolic names to a set of integer values. This is especially useful for creating a list of options that a variable can hold, without using numeric indices that are hard to remember. For example, if you want to define a set of courses, you can use an `enum` type to represent them with values like `ALGEBRA`, `BEGINNING_SPANISH`, `ASTRONOMY`, and so on. By using enums, you can make your code easier to read and maintain.
Consider the syntax for defining an `enum` in C++:

• Use the `enum` keyword followed by the name of the `enum` type, in this case, `courseType`.
• List the possible values within curly braces `{}` separated by commas. These values are commonly called enumerators.
• Each enumerator's value defaults to the index starting from zero.

Here is how you define it:

`enum courseType { ALGEBRA, BEGINNING_SPANISH, ASTRONOMY, GENERAL_CHEMISTRY, PHYSICS, LOGIC };`
This snippet sets up a `courseType` with six possible options each uniquely identifiable.

variable declaration

Declaring variables in C++ is fundamental as it allows you to create storage locations for the data your program will process. Each variable has a type, name, and optionally an initial value.
In context with `enum`, once you've defined your `enum` type, you need to declare a variable that can hold any of its values. Just like declaring variables of built-in data types, you use the `enum` type followed by the variable's name.

• First, you specify the type of the variable, which, in this case, is our defined `enum`, `courseType`.
• Next, you provide the name of the variable, such as `newClass`.
• You can later initialize this variable with any of its enum values.

Here is how you declare the variable `newClass` that can hold `courseType` values:
`courseType newClass;`
This declaration means `newClass` can hold any value from `ALGEBRA` to `LOGIC`, effectively using the symbolic names for easy management and readability.

input/output streams

In C++, input and output operations, also known as I/O, are handled using streams from the `iostream` library. This library provides a standard way to perform input/output operations with console and files.

• The `cout` object is used for output operations, allowing you to display text and variables on the console.
• The `cin` object is used for input operations, permitting user input via the console.
• Both `cout` and `cin` operations are part of the `iostream` header, so don't forget to include it.

When working with enums, converting values for template output can be tricky, as they are inherently integers in the background. Thus, an array of strings can represent symbolic names for easier output.
Example for outputting `newClass`:

```cpp #include const char* courseNames[] = {"ALGEBRA", "BEGINNING_SPANISH", "ASTRONOMY", "GENERAL_CHEMISTRY", "PHYSICS", "LOGIC"}; std::cout << courseNames[newClass] << std::endl; ```
For input, you may be required to enter an integer value corresponding to the enum index. `` can achieve this input:
```cpp int input; std::cin >> input; ```
This code captures user input and can then be converted to the `enum` type.

type casting

Type casting is converting a variable from one data type into another. In many scenarios, this occurs implicitly in C++, but at times explicit conversion using `static_cast` or other mechanisms is required for safety and clarity.

• `enum` types in C++ are stored as integers, so you might need to convert integers back to `enum` for assignments or calculations.
• Use `static_cast` to explicitly change types where necessary, especially when moving `enum` values around or dealing with input data.
• When working with enums, type casting is key for incrementing or cycling through values.

For example, to advance the `newClass` variable to the next value in `courseType`, you can cast and increment it as follows:

```cpp newClass = static_cast(newClass + 1); ```
This code snippet converts `newClass` to an integer, adds one, and casts it back to `courseType`. If the increment exceeds the defined range, you need to handle these cases to avoid runtime errors and undefined behavior.