Question

include 3 using std::cout; 4 using std::endl; 5 6 int cube( int y ); // function prototype 7 8 int main() 9 { 10 int x; 11 1… # 1 // Exercise 6.2: Ex06_02.cpp 2 #include 3 using std::cout; 4 using std::endl; 5 6 int cube( int y ); // function prototype 7 8 int main() 9 { 10 int x; 11 12 for ( x = 1; x <= 10; x++ ) // loop 10 times 13 cout << cube( x ) << endl; // calculate cube of x and output results 14 15 return 0; // indicates successful termination 16 } // end main 17 18 // definition of function cube 19 int cube( int y ) 20 { 21 return y * y * y; 22 } // end function cube

Short answer

The program outputs the cube of numbers 1 to 10, each on a new line.

Step-by-step solution

Analyze the Program Layout

The program includes the C++ iostream library and defines the function prototype for `cube`. The `main` function iterates through numbers 1 to 10. For each number, it calls the `cube` function to compute the cube and then outputs the result.

Understand the Function Prototype

The line `int cube(int y);` signifies a function prototype. This informs the compiler that a function named `cube` will be used, which takes an integer argument and returns an integer.

Loop through Numbers

The `for` loop defined with `for (x = 1; x <= 10; x++)` loops over integers starting from 1 up to 10, one by one.

Cube Calculation and Output

For each iteration, the `cube(x)` function is called with the current value of `x`, and its result is printed using `cout`. This is done with the line `cout << cube(x) << endl;`.

Function Definition

The `cube` function takes an integer `y` and returns the cube of `y` by computing `y * y * y`. This function is defined after the `main` function.

Key concepts

Function Prototype

In C++, a function prototype is an important declaration found at the beginning of the code, before the main function. It informs the compiler about the function's name, its return type, and its parameters. This is crucial for enabling the function to be called before its actual definition in the program.

In our example, the line `int cube(int y);` is the function prototype for the `cube` function.

• It specifies that `cube` is a function that will take a single integer argument.
• The function will return an integer value, which in this program is the cube of the passed integer.

The prototype helps the compiler validate function calls and ensures they match the defined signature, even if the function definition comes later in the code. This step is pivotal for proper program compilation and avoids "undetermined function" or related errors.

For Loop

Loops are a fundamental part of programming, allowing for repetitive execution of a block of code. The `for loop` is particularly useful when the number of iterations is known beforehand and is frequently used in C++ programming.

In this code example, the for loop is defined as `for (x = 1; x <= 10; x++)`. Here's how this structure works:

• Initialization: It starts by setting the initial value of the loop counter `x` to 1.
• Condition: It checks whether `x` is less than or equal to 10. If true, the loop continues; otherwise, it stops.
• Increment: After each iteration, the value of `x` is incremented by 1 using `x++`.
• Body: Inside the loop, the `cube(x)` function is called, and its output is displayed using `cout`.

The `for loop` in this program is structured to run exactly ten times, calculating and printing the cube of each number from 1 to 10.

Function Definition

The function definition specifies the actual block of code that is executed when the function is called. It describes how the result is computed and returned. Let's examine the `cube` function definition in our example:

The line `int cube(int y)` defines this function. Here's a breakdown of its components:

• A keyword `int` specifies that the function will return an integer value.
• The name `cube` is an identifier for the function.
• Inside the parentheses, `(int y)` declares an integer parameter `y`, which receives the value passed when the function is invoked.

The body of the function appears next, between the curly braces `{}`:

• Return Statement: `return y * y * y;` carries out the necessary calculation and sends back the cube of `y` to the calling function.

This function is defined after `main`, allowing the flow of execution in `main` to call `cube` efficiently with each loop iteration. Function definitions are essential in modular programming as they encapsulate specific logic, enhancing both code readability and reusability.