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 #include //Line 1 using namespace std; //Line 2 int one; //Line 3 void hello(int&, double, char); //Line 4 int main() //Line 5 { //Line 6 int x; //Line 7 double y; //Line 8 char z; //Line 9 . . . hello(x, y, z); //Line 10 . . . hello(x, y - 3.5, 'S'); //Line 11 . . . } //Line 12 void hello(int& first, double second, char ch) //Line 13 { //Line 14 int num; //Line 15 double y; //Line 16 int u ; //Line 17 . . . } //Line 18

Short answer

Function prototype: Line 4; Function heading: Line 13; Function body: Lines 14-18; Function call: Lines 10, 11. Global variable: `one`. Local variables: `x`, `y`, `z`, `num`, `y`, `u`. Reference parameter: `int& first`.

Step-by-step solution

Identify Function Prototype

The function prototype is declared on Line 4: `void hello(int&, double, char);`. This statement lets the compiler know about the function's name, return type, and the types of parameters it will accept but does not define the function itself.

Identify Function Heading

The function heading is the part of the function where the function is actually defined and is present on Line 13: `void hello(int& first, double second, char ch)`. This heading specifies the function's name, parameters, and return type.

Identify Function Body

The function body contains the actual code that will execute when the function is called. It begins at Line 14 and ends at Line 18, enclosed in curly braces { }. The body of the function `hello` includes the code block between these lines.

Identify Function Definition

A function definition includes both the function heading and the function body. In this code, the function `hello` is fully defined on Lines 13 to 18.

Identify Function Call Statements

Function calls are made in the `main` function to execute the `hello` function. These calls are on Line 10: `hello(x, y, z);` and Line 11: `hello(x, y - 3.5, 'S');`.

Identify Formal Parameters

Formal parameters are declared in the function heading of `hello`, specified on Line 13: `int& first, double second, char ch`. These are placeholders used when defining the function.

Identify Actual Parameters

Actual parameters are the values passed to the function during a function call. For the call `hello(x, y, z);` on Line 10, `x`, `y`, and `z` are the actual parameters. Similarly, for the call on Line 11, `x`, `y - 3.5`, and `'S'` are the actual parameters.

Identify Value and Reference Parameters

In the function `hello`, `int& first` is a reference parameter because of the `&`, allowing modification of the argument. `double second` and `char ch` are value parameters where copies are made and no modifications affect the original data.

Identify Local Variables

Local variables are defined within a function and accessible only there. In the `main` function, `x`, `y`, and `z` (Lines 7-9) are local. Within `hello`, `num`, `y`, and `u` (Lines 15-17) are local.

Identify Global Variables

Global variables are declared outside of any function and accessible throughout the code. The variable `one` is declared on Line 3, making it a global variable accessible by both `main` and `hello` functions.

Key concepts

Function prototype

In C++, a function prototype is an essential declaration that informs the compiler about a function's structure before its actual implementation. It essentially provides three vital pieces of information: the return type, the function name, and the list of parameter types the function expects.
This is accomplished without giving any specifics about how the function performs its task. The function prototype in the provided code is found on line 4: `void hello(int&, double, char);`. Here, `void` indicates that the function does not return a value, and `hello` is the name of the function.
The three parameters - an integer passed by reference (`int&`), a double, and a char - inform the function about the variable types it should expect.
The importance of the function prototype lies in its role in enabling the functions to be used prior to definition, or even in other files, facilitating better organized and modular code.

Local and global variables

Variables in C++ can be classified based on their scope, with local and global variables being the two primary categories.
Local variables are created within a function or a block and can only be accessed from within that function or block. For instance, in the given code, variables `x`, `y`, and `z` defined in the `main` function (lines 7-9) are local to `main`. Similarly, `num`, `y`, and `u` (lines 15-17) are local to the `hello` function.
Conversely, global variables are declared outside of any function and are accessible from any part of the code. In the sample code, the variable `one` is declared on line 3, making it a global variable.
Global variables should be used judiciously, as excessive use can lead to code that is difficult to debug and maintain, given the potential for unintended side-effects from various parts of the program modifying the same variable.

Reference and value parameters

Parameters in C++ functions can be passed either by value or by reference, and understanding this distinction is crucial in managing function behavior effectively.
When a parameter is passed by value, as with `double second` and `char ch` in the function `hello`, the function creates a copy of the argument's value. This means changes made to the parameter inside the function don't affect the original variable.
Conversely, reference parameters allow the function to directly access and modify the original variable itself. This is evident in `int& first`, where the `&` sign indicates a reference parameter.
Due to this property, reference parameters are generally more efficient for passing large objects or when the function needs to modify the original variable. However, they can lead to side effects if not handled properly, as changes affect the calling environment. Thus, mastering both concepts is pivotal to writing efficient C++ programs.