Question

Identify the following items in the programming code shown below: a. Function prototype, function heading, function body, and function definitions. b. Function call statements, formal parameters, and actual parameters. c. Value parameters and reference parameters. d. Local variables and global variables. e. Named constants. #include //Line 1 using namespace std; //Line 2 const double NUM = 3.5; //Line 3 int temp; //Line 4 void func(int, double&, char); //Line 5 int main() //Line 6 { //Line 7 int num; //Line 8 double one; //Line 9 char ch; //Line 10 func(num, one, ch); //Line 11 cout << num << " " << one << " " << ch << endl; //Line 12 func(16, one, '%'); //Line 13 cout << num << " " << one << " " << ch << endl; //Line 14 return 0; //Line 15 } //Line 16 void func(int first, double& second, char ch) //Line 17 { //Line 18 int num; //Line 19 double y; //Line 20 int u; //Line 21 num = 2 * first; //Line 22 y = second * first; //Line 23 u = static_cast (ch); //Line 24 second = num + y * u; //Line 25 }

Short answer

The code includes a prototype on Line 5, `func` definition from Lines 17-25, calls on Lines 11 and 13, local (`num`, `one`, `ch`, `y`, `u`) and global (`temp`) variables, a named constant (`NUM`), and value/reference parameters `first`, `ch`/`second`.

Step-by-step solution

Identify Function Prototype

The function prototype in the code is on Line 5: `void func(int, double&, char);`. This tells the compiler about the function name, return type, and the types of parameters it takes.

Identify Function Heading and Body

The function heading is on Line 17: `void func(int first, double& second, char ch)`. The function body is the block of code within curly braces starting from Line 18 to Line 25.

Identify Function Definitions

The function definition includes both the function heading and body, describing the entire implementation. It is from Line 17 to Line 25 for the function `func`.

Identify Function Call Statements

The function call statements are where the function `func` is invoked: `func(num, one, ch);` on Line 11 and `func(16, one, '%');` on Line 13.

Identify Formal Parameters

Formal parameters are found in the function definition on Line 17: `int first, double& second, char ch`.

Identify Actual Parameters

Actual parameters are found within the function call statements: `num, one, ch` in Line 11 and `16, one, '%'` in Line 13.

Identify Value Parameters and Reference Parameters

In the function definition on Line 17, `int first` and `char ch` are value parameters. `double& second` is a reference parameter because of the `&` symbol, indicating the parameter is passed by reference.

Identify Local Variables

Local variables are declared within a function. In `main`, they are `int num`, `double one`, and `char ch` (Lines 8-10). In `func`, they are `int num`, `double y`, and `int u` (Lines 19-21).

Identify Global Variables

`int temp` (Line 4) is a global variable because it is declared outside all functions.

Identify Named Constants

`const double NUM = 3.5;` on Line 3 is the named constant because it uses `const` and is declared at the global scope.

Key concepts

Function Prototype

In C++, a function prototype gives the compiler a sneak peek of how a function is called within a program. It's like a roadmap for the compiler to understand what to expect from a function.
In the code above, the function prototype is defined on Line 5: `void func(int, double&, char);`. This line informs the compiler that `func` is the name of the function, with a return type of `void`, meaning it doesn’t return a value.
It also specifies that the function takes three parameters: an integer, a double reference, and a character.

A function prototype allows you to declare a function before actually defining its body in your program. It's crucial because it helps prevent errors by ensuring that all function calls are consistent with their definitions. Without it, the compiler would not know how to handle function calls properly within the code.

Function Parameters

Parameters in C++ functions are placeholders used for passing data into functions. They come in two types:

• Formal Parameters
• Actual Parameters

**Formal Parameters** are defined in the function's definition line. These are like templates that specify what kind of information you'll need to give a function. For example, in Line 17: `void func(int first, double& second, char ch)`, `first`, `second`, and `ch` are formal parameters. They define the kind of information the function `func` expects to receive.

**Actual Parameters** are the actual values or variables supplied to the function during the function call. In this code, they appear on Line 11 and Line 13. For the call `func(num, one, ch);`, `num`, `one`, and `ch` are the actual parameters, which are passed into the function when it's called.
Understanding the distinction between formal and actual parameters is vital. It ensures you use functions correctly by providing the expected number and types of arguments each time you make a call.

Local and Global Variables

Variables in C++ can be categorized into local and global variables based on their scope and lifetime.
**Local Variables** are declared within a function and can only be accessed within that function. They are created when the function is called and destroyed when the function exits. In the function `main()`, for instance, `int num`, `double one`, and `char ch`, defined on Lines 8-10, are local variables. They are only accessible within the `main()` function. Similarly, `int num`, `double y`, and `int u`, declared within `func()` on Lines 19-21, are local to that function and not accessible outside of it.

**Global Variables** are defined outside of all functions and therefore can be accessed by any function throughout the program. The variable `int temp`, declared on Line 4, is a global variable. This means it is available for use in both `main()` and any other function defined after its declaration.
Understanding the scope and lifetime of variables is crucial for memory management and ensuring your program behaves as expected.

Named Constants

Named constants in C++ are variables whose values cannot be changed once they have been set. These constants are defined with the keyword `const` and must be initialized at the time of declaration.
An example in the program is `const double NUM = 3.5;` found on Line 3. Here, `NUM` is a named constant with a value of 3.5, and as such, its value cannot be altered later in the program. Named constants provide a clear, easy way to use universal values within your code, improving readability and reducing the likelihood of errors via accidental modification.

Using named constants is a best practice in programming, particularly when the value will be reused multiple times throughout your code. It makes your code easier to maintain and understand by conveying meaning through descriptive names.